Assertion (A): Most volcanic eruptions take place near plate margins.

Reason (R): When these plates slide past each other or collide against each other due to intense heat inside the earth's core, their edges produce faults along the lines of weakness.

1. Both A and R are true and R is the correct explanation of A.
2. Both A and R are true but R does not explain A.
3. A is true but R is false.
4. A is false but R is true.

Both A and R are true and R is the correct explanation of A.

Explanation — The earth's crust is made up of a series of movable plates. When these plates slide past each other or collide against each other due to intense heat inside the earth's core, their edges produce faults along the lines of weakness. It is along these plate boundaries that the crust is weakened and through which the hot magma gushes out leading to volcanic eruption.