The correct option is Option 4: Sprint Burndown. A burndown chart displays the amount of work remaining in a sprint. It is an essential tool for Agile teams to track their progress and ensure they are on track to meet their sprint goals.

The JIRA database stores all the issue data used by the application, including details about projects, workflows, users, and their activities.

When integrating JIRA with external tools, it's important to define clear processes and workflows. This ensures smooth communication and collaboration between JIRA and other tools, leading to better project management and efficiency.

A post-function in a JIRA workflow is an action that occurs after a transition is executed, such as sending notifications, updating fields, or triggering additional processes. It allows for automation and customization of workflow behavior based on specific events, enhancing the efficiency and effectiveness of the workflow. Understanding post-functions is important for configuring workflows to meet the specific needs of the project and team.

In JIRA, a project serves as a container for organizing and managing issues, which can represent tasks, bugs, features, or any other unit of work within the project.

The "Sub-task" issue type in JIRA is typically used to represent a small, well-defined piece of work within a larger project. Sub-tasks are often used to break down larger tasks or user stories into more manageable sub-components, allowing for better tracking and management of work. They are commonly used to divide work among team members or to represent tasks that are required to complete a larger user story or task.

To install a JIRA plugin or add-on, users typically navigate to the "Plugins" section of their JIRA instance. This section allows users to manage and install plugins, extending the functionality of their JIRA instance according to their specific needs.

"Gadgets" on a JIRA dashboard refer to the various visual elements or widgets that display specific information or metrics related to projects, teams, or issues. These gadgets can include charts, graphs, statistics, or lists, providing users with real-time insights into project status, progress, and performance. Gadgets are useful for reporting as they enable users to customize their dashboards with relevant metrics and data visualizations, making it easier to track key performance indicators, identify trends, and communicate project status to stakeholders effectively. By configuring gadgets on their dashboards, users can create personalized reporting tools tailored to their specific needs and preferences.

In JIRA, sub-tasks are created under parent issues, which can be either epics, stories, bugs, or other issue types depending on your project's configuration. The parent issue defines the context for the sub-task.

Burndown charts in JIRA visualize the amount of work remaining over time, providing insights into project progress and trends.