【单选题】

project cash reserves are often used for adjustment in escalation factors which may be beyond the control of the project manager. other than possibly financing (interest) costs and taxes, the three most common escalation factors involve changes in:

a. overhead rates, labor rates and material costs.
b. overhead rates, schedule slippages, and rework.
c. rework, cost-of-living adjustments, and overtime.
d. material costs, shipping cost, and scope changes.
e. labor rates, material costs, and cost reporting.