请教GMATprep一道数学题

 可能是读不懂题目，怎么答案会是C ?

For a finite sequence of nonzero numbers, the number of variation in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive term is negative. What's the number of variation in sign for the sequence 1, -3, 2, 5, -4, -6 ?

A. one   B. Two  C. Three  D. Four  E. Five

For a finite sequence of nonzero numbers, the number of variation in sign is defined as the number of pairs of consecutive terms of the sequence for which the product of the two consecutive term is negative. What's the number of variation in sign for the sequence 1, -3, 2, 5, -4, -6 ?

A. one   B. Two  C. Three  D. Four  E. Five

我認為題目故意讓你以為它很難

我答對但不知道是否理解正確

就是連續兩個數字的積為負

所以就是 (1,-3), (-3,2), (5, -4)囉