The trick here is to notice that:

1] This is actually a disguised Geometric Progression from the 3rd term onwards: 2, 3,

5, 10, 20, 40, 80...2] Because the Geometric Progression starts from the 3rd term of the set, the nth term in the set is actually the (n-2)th term of the Geometric Progression part of the set

Now armed with these two observation, apply the formula for nth term of any Geometric Progression = b X r^(n-1); remember b is 5 and n will be the 18th and 22nd term respectively, NOT 20th and 24th because of the 2nd observation above.

h = 18th term of the GP = 5 X 2^17

k = 22nd term of the GP = 5 X 2^21

k/h = 2^4 = 16

Therefore D is the correct answer.

Hope this helped.

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The only ability the GMAT is an indicator of...is the ability to do well on the GMAT.