Question Pack SC. So every one proceed only if not contemplating to purchase it.

A row of upright fan-shaped plates running down the spine provided the Stegosaurus dinosaur with an especially efficient solar heating and cooling system to allow them to move comfortably through different climatic regions.

A)to allow them to move comfortably
B)to allow it a comfortable movement
C)that allowed it to move comfortably
D)that allowed their comfortable movement
E)Allowing them to move comfortably
OA C

Hello Guru,
can you tell the difference between B and C?
in that clause vs infinitive, how to choose one?
Thanks