The Bootstrap 'card' component is primarily used for presenting content in a flexible container, allowing you to display various types of content, such as text, images, and links, in a visually appealing manner.

Bootstrap JS enhances a website by adding dynamic features to the user interface, such as sliders, modals, and tooltips, making the site more interactive and engaging.

Bootstrap's grid system adapts fluidly, allowing seamless transitions between portrait and landscape modes on mobile devices, ensuring a consistent layout.

Bootstrap's media queries enhance mobile-first design by allowing developers to define styles for small screens first and then override them for larger screens. This approach ensures that the default styles are optimized for mobile devices, providing a responsive design that progressively enhances as the screen size increases.

Using descendant selectors is common when modifying Bootstrap styles to increase specificity. Descendant selectors target elements that are descendants of a specified element, allowing you to apply styles more precisely.

The correct option is !important. The !important declaration in custom CSS can unintentionally override Bootstrap's responsive utilities. It gives a style rule the highest specificity, making it challenging for other styles to override it. Careful use of !important is crucial to avoid unintended style conflicts with Bootstrap's responsive features.

The d-none class in Bootstrap is used to hide an element. It sets the display property to none, making the element invisible on the page. This is commonly used for responsive design when you want to hide an element on certain screen sizes or devices. It's more efficient than using custom CSS to hide elements.

To make a Bootstrap navbar fully accessible, it's essential to leverage ARIA (Accessible Rich Internet Applications) roles and attributes. These attributes help in providing additional information to assistive technologies, making the navigation experience more meaningful for users relying on screen readers. Options 2, 3, and 4 are incorrect because... (provide reasons)

Modals in Bootstrap are primarily used for displaying pop-up dialogs, prompting users for input, or showing additional content without navigating away from the current page. They are useful for creating interactive and user-friendly interfaces.

The correct option is Progress. The Progress component in Bootstrap is specifically designed for displaying progress bars, making it an ideal choice for visualizing the progress of a task or process.