【正确答案】 D

【答案解析】Given that x ^y =64, there are a variety of values for x and y. For example, if x=2, then y=5, such that 25=64. However, if x=8, then y=2 such that 8 ² =64. Both examples are valid, yet in the first, x＞y and in the second, x＜y. Therefore, a relationship cannot be determined from the information given.