In a certain bathtub, both the cold water and the hot water fixtures leak. The cold water leak alone will fill an empty bucket in c hours, and the hot water leak would fill the same bucket in h hours, where c < h. If both fixtures began to leak at the same into the empty bucket at their respective constant rates and consequently it took t hours to fill the bucket, which of the following must be true?
I. 0 < t < h
II. c < t < h
III. c/2 < t < h/2

A) I only
B) II only
C) III only
D) I and II
E) I and III

ans E
Can someone please give the explanation