Help and Hello!

I'm trying to look up and match a value from each row in column A to a value
in column C and return the associated value for that row in column B. Example:

A B C D
14 0.1 14 0.1
14 0.1 15 0.2
15 0.2 16 0.3
15 0.2 17 0.5
16 0.3 18 0.8

Thanks so much in advance!!!
Chris