Answer is choice B. Here's how:

Firstly, it is not mentioned that the figure not drawn to scale, which means, it is drawn to scale.

As we know |a-b| = |b-a|, and |x-5| = |5-x|

So we can simplify Quantity B as follows:

Quantity A: |x-5| - |a-b|
Quantity B: |a-b| - |x-5|

Now, we need to see whether |x-5| is greater or |a-b|. As we know |x-y| gives distance between x and 5, while |a-b| gives distance between a and b, therefore. After looking at the number line we can see that clearly distance between a and b is greater than distance between x and 5.

Thus, Quantity B is greater.