Which of these statements regarding time-cost tradeoffs in Critical Path Method (Project Crashing) networks is always true? (explain answer)

a. Crashing is not possible unless there are multiple critical paths.

b. Crashing shortens the critical path by assigning more resources to one or more non-critical tasks.

c. Activities not on the critical path can never be on the critical path, even after crashing.

d. Crashing shortens the project duration by assigning more resources to one or more of the tasks.

e. Crashing need not consider the impact of crashing an activity on other paths in the network

f. None of the above.