How much more secure is 56 bit encryption opposed to 40 bit encryption?

A.
16 times

B.
256 times

C.
32768 times

D.
65,536 times

Explanation:
2 to the (56-40)th power – 2 to the 16th power = 65536
Note:
2 to the power of 40 = 1099511627776
2 to the power of 56 = 72057594037927936
72057594037927936 / 1099511627776 = 65,536