The number in each question bleow is to be codified in the following code:
Digit 7 2 1 5 3 9 8 6 4
Letter W L M S I N D J B
->  184632

Answer: D. MDBJIL

As given, 1 is coded as M,
8 as D,
4 as B,
6 as J,
3 as I   and
2 as L.
So, 184632 is coded as MDBJIL.