As we dicussed, when airlines use preventative maintenance to assure the standard of zero crashes per year, they are using $\_\_\_\_\_\_$ control to improve safety, and when they use employee$-$staffed, curbside checkpoints for checking$-$in bags to minimize number of bags lost, they are using $\_\_\_\_\_$ control.

Question $28$ options:

A$)$

preliminary, concurrent

B$)$

feedback, concurrent

C$)$

preliminary, feedback

D$)$

preliminary, preliminary

E$)$

concurrent, feedback