两汉时期，（）是指今天的甘肃玉门关和阳关以西，也就是今天新疆地区和更远的地方。

The critical chain ______ .

A．focuses on managing the resources applied to buffer activities

B．alters the required dependencies in the project schedule to optimize resource constraints

C．adds duration buffers that are work schedule activities to maintain focus on the total float of network paths

D．adds duration buffers that are non-work schedule activities to maintain focus on the planned activity durations