The subordinate clause is "When the delivery man arrives" because 1. it is introduced by "when" and 2. we can ask question to the main clause about this one.
I believe the answer is a.)
Answer:
C
Explanation:
The KKK believed African Americans were better off being slaves and didn't deserve any rights.
Answer:
3rd button
Explanation:
You are correct, the other sentences are grammatically incorrect.