单选题 A PERT cost network may display both expected and actual times and costs, which allow for breaking down variances into spending variances and activity time variances. Which one of the following calculations would be used to compute the activity time variance?

A、 (actual time less expected time) x (expected cost).
B、 (actual time) x (actual cost less expected cost).
C、 slack time less normal time.
D、 critical path time less slack time.

【正确答案】 A

【答案解析】