Answer:
option B
0 N
Step-by-step explanation:
Since, two forces are acting on the child sitting in a seat
Fn = 100N
Fg = -100N
Resultant force = sum of all forces
= 100 + (-100)
= 0
The two forces have same magnitude but in opposite directions, so the net force (resultant of the two forces) is zero.
And,
secondly, the child is stationary so it obvious that resultant force acting in the object is zero.