When embedding YouTube videos, it's vital to ensure you have the right to use the content. Just because a video is on YouTube doesn't mean it can be freely embedded anywhere. The best approach is to use videos where the owner has granted permission, either directly or through the video’s licensing terms. While YouTube might handle some copyright issues (like takedowns), the responsibility of adhering to copyright laws when embedding videos rests with the website owner or developer. 

The type attribute in a source tag within an audio or video tag specifies the media file's MIME type, such as "video/mp4" or "audio/mp3". This informs the browser about the file format and potentially helps it select the most appropriate source when there are multiple source tags provided. This enhances compatibility as different browsers may support different file formats. 

The quotes CSS property is used to specify the type of quotation marks for embedded quotations. This is useful when customizing the type of quotation marks that appear before and after a element. For instance, different languages and cultures use different styles of quotation marks, and this property helps in tailoring the appearance of the content according to the target audience. 

The tag is used to define the main content of the HTML document. Everything that appears between the opening and closing tags will be displayed in the main browser window. This is where all the content, like text, images, links, and more, is placed. 

The element is used within a tag to group related elements under a single label. This can help in categorizing options within a dropdown, making it more user-friendly, especially when dealing with long lists of options. It enhances the visual clarity of dropdown lists by providing a hierarchical structure. 

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How can the nth-child pseudo-class selector be used to style table rows?

Difficulty level

• To select and style the first row of a table. 
• To style every nth-row in a table. 
• To style rows based on their child elements. 
• To style the table header only. 

The :nth-child() pseudo-class selector in CSS is used to match elements based on their position in a group of siblings. In the context of table rows (

elements), it can be employed to apply styles to every nth-row. For example, tr:nth-child(even) { background-color: #f2f2f2; } will apply a background color to every even row in a table, creating a zebra-stripe effect. 

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How do you ensure that an image maintains its aspect ratio when resized?

Difficulty level

• Set the max-width property to 100%. 
• Use a fixed width and height in pixels. 
• Use the aspect-ratio CSS property. 
• Use the width attribute and leave the height attribute unset (or vice versa). 

Ensuring an image maintains its aspect ratio when resized is critical for consistent design and user experience. By setting only one dimension (either width or height) and leaving the other unset, the browser will automatically scale the unset dimension proportionally, preserving the image's original aspect ratio. 

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To pre-select an option in the dropdown list, use the ______ attribute.

Difficulty level

• default 
• checked 
• select 
• selected 

The selected attribute is used within the tag to pre-select an option in a dropdown list when the page loads. By setting this attribute, the corresponding option will appear as the default choice in the dropdown, making it easier for users if a specific option is commonly selected. 

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The ______ tag is utilized to create a bulleted list within the HTML body.

Difficulty level

•  
•  
•  
•  
  The

  tag stands for "unordered list" and is used to create a list of items with bullet points. Each individual item within this list is marked by the
  • (list item) tag. The
    represents the entire list structure, while
    • represents each point. 

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