3題ｑｕｅｓｔｉｏｎ～ｐｌｅａｓｅ　ｈｅｌｐ

I believe this is ____ book in this library.

a. a thick
b. the thicker
c. most thickest
d. the thickest

The stranger introduced himself and ____ he had known my father for a long time.

a. had said
b. has said
c. said
d. will say

We are ordering in large quantity. Could you offer us a ____ price?

a. better than
b. better
c. best
d. the best