声明一个方法:提供Student对象数组按照学号升序排列的判断条件()
A.- (BOOL))compareWithNumberForAscendSort:(Student*)otherStudent B.-(NSInteger)compareWithNumberForAscendSort:(Student*)otherStudent C.-(NSComparisonResult)compareWithNumberForAscendSort:(Student*)otherStudent D.+(int)compareWithNumberForAscendSort:(Student*)otherStudent