I'm not the greatest at grammar, but I think the very first one is incorrect. It should just be a comma, then the second just a comma as well, but the last one is correct. (I have no idea, I am sorry if you get it wrong.)
Answer: C
Explanation: It would be the most responsible and polite thing to do, not just call out someone else or leave the customer expecting a call.
Answer:
Isolate is the best word I know.
Explanation:
But if you have choices, and it isn't a choice, then tell me your choices.
