How to calculate distance based on velocity time graph

Ithink the answer is c but then again i'm probably wrong

It's because 3 if it was 10 it wouldn't look right do it goes up to 4d

I'm having some difficulty seeing the diagram clearly.but the question says there's a net inward force on the object.so we know right away,  from newton's 2nd law of motion, thatthat baby is accelerating.  it doesn't even matter which way thenet force is pointing.  if there's any net force, then either theobject's speed or else its direction must be changing.