Determine the fraction for option A.
In option A, eight foot ribbon is cut into five equal part. So length of each part is,

In option B, eight hour bus trip is divided among five equal parts. So each part consist of,

In option C, five pounds divided among 8 horses. So each horse get,

In option D, 8 cookies shared among 5 friends, so each friend get,

Only option C can represented by 5/8.