Last week local shrimpers held a news conference to take some credit for the resurgence of the rare Kemp's ridley turtle, saying that their compliance with laws requiring that turtle-excluder devices be on shrimp nets protect adult sea turtles.
A. requiring that turtle-excluder devices be on shrimp nets protect
B. requiring turtle-excluder devices on shrimp nets is protecting
C. that require turtle-excluder devices on shrimp nets protect
D. to require turtle-excluder devices on shrimp nets are protecting
E. to require turtle-excluder devices on shrimp nets is protecting

OA is B, can someone explain what is wrong with A.

Also why can't we use Infinitive forme of to require here.