Question

Select the independent clause.

If the construction work on Main Street has begun, you must take the detour down
First Avenue.

Answer 1

"you must take the detour down First Avenue." is the independent clause.

Answer 2

Answer: The second half of the sentence, after the comma. "you must take the detour down First Avenue."

Explanation: An independant clause can form a sentence on its own. A dependable clause will be like an incomplete sentence.