I think A. is fine, such as:

A. Which of the above definitions is the most accurate in describing the meaning of "bombastic" in that interview?

For B., I think its more difficult to understand the intent, though you could say:

B. Which of the above definitions fits more accurately the meaning of "bombastic" in that interview?

"does it fit" is a problem and should be "fits".

Also you could start with "In that interview, ..." rather than at the end. Then, its clear from the start you are asking something about the interview.

I think A. is fine, such as:

A. Which of the above definitions is the most accurate in describing the meaning of "bombastic" in that interview?

For B., I think it's more difficult to understand the intent, though you could say:

B. Which of the above definitions fits more accurately the meaning of "bombastic" in that interview?

"does it fit" is a problem and should be "fits".

Also you could start with "In that interview, ..." rather than at the end. Then, it's clear from the start you are asking something about the interview.