Question

In which case will the object move due to an unbalanced force?

A.
Up = 300 N
Right = 300 N
Down = 300 N
Left = 250 N

B.
Up = 450 N
Right = 450 N
Down = 450 N
Left = 450 N

C.
Up = 300 N
Right = 400 N
Down = 300 N
Left = 400 N

D.
Up = 550 N
Right = 200 N
Down = 550 N
Left = 200 N

Answer 1

To get your answer, just see which one has unequal forces in opposite directions.

Answer 2

A. Up = 300 N Right = 300 N Down = 300 N Left = 250 N

up and down cancel each other with 300N a piece, but right force has 300N and the left opposing force only has 250N, so the force from the right will push toward the left

Answer 3

only A has unbalanced forces. moves right 50N net force
the others have up=down, left=right. no motion.
question does not make clear whether "left" means "from the left" or "toward the left," but I would suspect the latter.