For a process with the following operations, what will be the activity efficiency if the process is run as an unprimed line?

Operation A Operation B Operation C Operation D

C$/$T mins $12141618$

Bottleneck C$/$T $18$

Shift time mins $300$

Group of answer choices

$67\mathrm{.}5\%$

$73\mathrm{.}3\%$

$72\mathrm{.}9\%$

$71\mathrm{.}7\%$