Column Matching and Data Pulling


I am looking for first, for two columns to match, let's call them A and C, if they match, I want Column D to have the same vaule as Column B.
A, B and C will all be hard entered, and I want D to change based on C

For Example:

ColumnA ColumnB ColumnC ColumnD
Row1 Hello 1 Adios 3
Row2 GoodBye 2 Hello 1
Row3 Adios 3 GoodBye 2

How would I go about doing this?