Explanation:

Option 4th is correct.

Statement 1st is correct: Newton's first law states that “if a body is at rest ,it remains in rest and if it is in uniform motion then it will continue its uniform motion untill an external force is applied on it”

• It explained that every body has the tendency to oppose the change in its state of rest or state of uniform motion.

• So according to Newton's first law - “Force is an external factor which can change the state of rest or state of uniform motion of an object”.

• In the first law, an object will not change its motion unless a force acts on it. In the second law, the force on an object is equal to its mass times its acceleration. In the third law, when two objects interact, they apply forces to each other of equal magnitude and opposite direction.

Statement 2nd is correct: Newton's second law states that the magnitude of the net external force on an object is Fnet=ma. Since the object experiences only the downward force of gravity, Fnet=w. We know that the acceleration of an object due to gravity is g, or a=g. Substituting these into Newton's second law gives. 

Statement 3rd is correct: Yes, Newton's first law is contained in the second law as if force is zero then the acceleration would be zero which means the body would remain in its state of rest or in state of constant motion.

• The first law of motion states that the position of an object, in motion or at rest, does not change unless some external force is applied to it.

• So, if no external force is acting on the object, we can write, .

• From the second law of motion, F = m x a .

• This gives, a = F m = 0 m = 0 .