Answer:
B) Who/Whose
Step-by-step explanation:
This would be more reasonable than the other choices listed.
A) Bill is a man which is interesting to talk with, but that stories about himself are so incredible that not many people believe them.
B) Bill is a man who is interesting to talk with, but whose stories about himself are so incredible that not many people believe them.
C) Bill is a man that is interesting to talk with, but what stories about himself are so incredible that not many people believe them.
D) Bill is a man whom is interesting to talk with, but when stories about himself are so incredible that not many people believe them.
Now, which of these sounds like the most grammatical and logical answer?
I may be wrong, but I do believe that B is the right answer. Thanks!