Answer:
C - 100% of 0.25
Explanation:
This answer is basically the same as 25% of 100, just worded differently to confuse you.
25 is 1/4th of 100, so this should be the answer. :)
If you're curious of what the other answers amount to:
One hundredth of 250 = 2.5
50% of 5 = 2.5
40% of 1 = 0.4