he following list represents CPM network of a project.

Activity Normal time $($day$)$ Crash time $($days$)$

Normal cost

Crash cost Predecessor

A $86$ $$1,000$ $$1,600---$

B $107$ $$2,000$ $$2,600---$

C $54$ $$500$ $$1,000$ A

D $97$ $$4,000$ $$4,200$ A$,$ B

E $21$ $$3,000$ $$4,000$ C$,$ D

Which activity should be crashed first to cut one day from the project's duration; how much is added to project cost?

Question $11$ options:

D; $$100$

B; $$200$

E; $$1000$

C; $$100$