“That some musicians play”-
Imagine that you had to take out part of the sentence. Ask yourself “how can I still have this sentence make sense after I take out a phrase?” You wil see that the phrase “that some musicians play” is not important to sentence and the reader’s understanding. Hope this helps!
The answer is c, all marines In France
The marker of the mofat has to make me do the vacation of the mofat.
You should read and get inspiration