When two forces act in the same direction, they are together.

Add

Explanation:

When two forces are acting in the same direction then there magnitude are added to each other

Let the first force is and second force is and when they act in same direction then their equivalent will be equal to

When they cat in opposite direction then their equivalent will be

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.