The answer is letter C.Weight (on Earth) is the force due to the mass of Earth attracting whatever mass is subject of discussion.
The force of attraction between any two masses is called Newton's Law of Universal Gravitation:


is simply a given constant.
If we're at the surface of Eath,

refers to the mass of the Earth,

to the mass of whatever is on the surface of Earth, and

to the radius of Earth.
Normally, we define a constant

to be equal to

; in which

is the mass of Earth and

the radius of earth;

happens to be around 9.8.
By that, we adapt the Law of Universal Gravitation to objects on the surface of Earth, we call that force Weight.

As you can see, weight is directly proportional to mass, more mass implies more weight.
You fallow the steps to figure out the complete answer of the question.
Force of gravity on an object is the weight of the object and is given by mass times accerelation due to gravity. The accerelation due to gravity is the accerelation of an object in free fall and is given by 9.8m/s^2. Given that the force of gravity acting on a child's mass on earth is 490 newtns, i.e. F = mg which means that 490 newtons = 9.8 times mass. Therefore, mass of the child is 490 / 9.8 = 50 kg.
Answer:
What is a Free Body Diagram?
The free body diagram helps you understand and solve static and dynamic problem involving forces. It is a diagram including all forces acting on a given object without the other object in the system. You need to first understand all the forces acting on the object and then represent these force by arrows in the direction of the force to be drawn.
Explanation:
KE=1/2 mv^2
=1/2(150kg)(15m/s)^2
=16875 kgms^-2