We try plugging in the options here

Let's try C as it's the choice in the middle
If Z=0, our subtraction remains intact,
We plug in Y=7, then 14 - 7= 7, so we still are on the right track,
Now plug in X=8, we carry 1 and add it to X, so X=8+1=9
And, 17-9=8, voilà!
Our answer choice would be (C)
Visual representation here,
8.740
-3.870
______
4.870