The correct answer is option 'C': the principle of superposition.

Explanation:
The principle of superposition is a fundamental concept in physics that allows us to find the resultant gravitational force acting on a particle due to a number of masses. It states that the total force acting on a particle is equal to the vector sum of the individual forces acting on it.

When multiple masses exert gravitational forces on a particle, each force acts independently of the others. The principle of superposition allows us to consider each force separately and then add them up to find the resultant force.

Here's a detailed explanation of how the principle of superposition works in finding the resultant gravitational force:

1. Gravitational force between two masses:
- According to Newton's law of universal gravitation, the gravitational force between two masses (m1 and m2) is given by the equation F = G * (m1 * m2) / r^2, where G is the gravitational constant and r is the distance between the masses.
- To find the force acting on a particle m due to one mass, you calculate the gravitational force using the above equation.

2. Superposition of gravitational forces:
- If there are multiple masses (M1, M2, M3, ..., Mn) acting on the particle m, we can find the gravitational force exerted by each individual mass using the equation mentioned above.
- The principle of superposition allows us to sum up all these forces to find the net or resultant gravitational force acting on the particle m.
- Mathematically, the resultant force F_net is given by F_net = F1 + F2 + F3 + ... + Fn, where F1, F2, F3, ..., Fn are the gravitational forces exerted by each individual mass.

3. Vector addition of forces:
- Since forces are vector quantities, their magnitudes and directions need to be considered while adding them.
- The vector sum of all the individual forces gives us the resultant force acting on the particle.
- The direction and magnitude of the resultant force can be determined using vector addition methods such as graphical methods or vector components.

So, using the principle of superposition, we can find the resultant gravitational force acting on a particle m due to a number of masses. By considering each individual force separately and adding them up, we can determine the net force on the particle.

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