In a chocolate store, there are vanilla

In a chocolate store, there are vanilla and chocolate flavor bon-bons only.
10% of the bon-bons are chocolate flavored, 90% of the rest are squashed.
What percentage of the bon-bons is vanilla flavored that are not squashed?

(a) 1%
(b) 5%
(c) 9%
(d) 10%
(e) 2%

The best answer is C.
Pick a number of bon-bons, like 100 for example.
10 are chocolate, 90% of the rest (0.9 x 90 = 81) are squashed.
That means that only 9 are vanilla and are not squashed.