Answer:
the first one
Step-by-step explanation:
An independent clause is simply a clause that makes sense on it's own.
So which ever answer choice makes sense on it's own is an independent clause and is likely the answer
Help us find your sisters purse. this is a independent clause because it makes sense without the dependent clause, so it might be the answer choice but let's look at the other answer choices just in case.
anywhere you want. this is a dependent clause because it doesn't make sense by itself. so this can't be the answer.
thinking there's nothing else to do. this clause overall just doesn't make sense so we can eliminate it.
bring back the car when you're done. this makes sense by itself meaning it's an independent clause
so its between the first and second one. which ever makes the most sense with the dependent clause is the answer.
Before you go, help us find your sisters purse.
Before you go, bring back the car when you're done.
The first one makes the most sense because in the second one, it's asking you to do an action before the action is done and when the action is done which is not grammaticality correct.