Sorry Eddie I think you are wrong too!
I have swung lots of aircraft compasses and calculate the deviation thus:
deviation = magnetic - compass
that is
D = M - C
(swap it around to get C + D = M , that is Cadburys Dairy Milk!)
All this Easterly and Westerly business is unnecessary for deviation on aircraft, it scares me, I have nothing to do with it. Unfortunately we are lumbered with it for variation for historical reasons.
If I am wrong there are many aircraft flying with wrong magnetic and gyro compasses!
The original question is simply solved with
CDMVT to get answer A.