【单选题】

Increasing resources on the critical path activities may not always shorten the length of the project because: 

A Certain activities are time-dependent rather than resource-dependent (i.e., using three ovens rather than one to bake a cake). 
B Safety, OSHA and EPA may have placed restrictions on the number of people used on certain activities or in the physical location of the project. 
C The skill level of the added resources might not be appropriate for the activities to be performed. 
D Adding more resources may create additional work and produce inefficiencies (i.e., additional people may need training and supervision.) 
E All of the above.