Landslides are primarily caused by -

B

magnetic energy

solar power

gravitational pull

beat

Gravitational pull

Explanation:

There are four fundamental forces in nature:

- Gravitational force: it is an attractive force exerted between all objects having mass. Its magnitude is proportional to the product of the masses and inversely proportional to the square of the distance between the objects.

- Electromagnetic force: it is the force exerted between electrically charged object. It can be either attractive ore repulsive. Its magnitude is proportional to the product of the charges and inversely proportional to the square of the distance between the objects.

- Strong nuclear force: it is the force responsible for holding protons and neutrons together in the nuclei of the atoms. It is attractive and acts only on a very short scale.

- Weak nuclear force: it is the force responsible for certain nuclear decay processes (radioactivity).

In this problem, landslides occur when certain masses of terrain are attracted towards the ground - they are attracted because of the gravitational force.

So, the correct answer is

gravitational pull