Question: How does this command alter the currently checked-out branch?

1. It resets the working branch to the first commit.
2. It sets HEAD to previous commit and leaves changes from the undone commit in the stage/index.
3. It deletes all previous commits and resets the repository history back to its initial state.
4. It keeps the HEAD at the current commit, but clears all previous commits.

Answer: The correct answer of the above question is Option B:It sets HEAD to previous commit and leaves changes from the undone commit in the stage/index.