In a Lake, there is a patch of lily pads. Every day, the patch doubles in size. It takes 25 days for the patch to cover the entire lake, how many days would it take the patch to cover half of the lake?  Select
A) 36
B) 2 ^ 4 * 3
C) 24
D) 38
E) 47

Rationale: "so 24 days answer c = 24"
Answer: C