Answer :

The correct answer is:

d. sidebar

Explanation:

1. The sidebar of a blog's theme typically contains widgets, recent activity, and main links that you want to highlight to your readers.
2. Widgets are small blocks that perform specific functions, like displaying recent posts, archives, search bars, etc.
3. Recent activity often includes recent posts, comments, or other interactions on the blog.
4. Main links in the sidebar are important navigation elements that can lead users to key sections of the blog, such as categories, archives, or important pages like the about page or contact page.

Therefore, the sidebar is the part of a blog's theme that commonly houses widgets, recent activity, and main links for easy access and navigation.