Match cells by columns

I need COLUMN B to show what is in COLUMN D depending on what is in COLUMN A with a formula:

(COLUMN A) (COLUMN B) (COLUMN C) (COLUMN D)
A(BOX 1) C(HAMMER) D(1234)
A(SCREWDRIVER) B(?) C(SCREWDRIVER) D(4321)
A(HAMMER) B(?)

A(BOX 2)
A(HAMMER) B(?)
A(SCREWDRIVER) B(?)