下列属于物流信息中计划信息的特点的是（）.

A.动态性强

B.时效性强

C.相对稳定性

D.更新速度较慢

“Design of experiments” is a statistical method that helps （）.

A．determine how various elements of a system interrelate

B．identify which factors may influence specific variables of a product or process

C．establish a standard by which to measure performance

D．compare actual or planned project practices to those of other projects