Answer:
the answer is either A or D but im putting my thoughts on A
hope it helps:)
Just write the email or letter you think would help best thats what im gonna go with
Required.
These two terms are related because they both mean necessary, essential, or needed. Required means that it's plainly needed. Vital is more dramatic, more serious, and it means that without it, there is no function.
I hope it's right!