Option 1 states that both the Assertion (A) and Reason (R) are individually true, and that R is the correct explanation of A.

The Assertion (A) states that the disintegration of Pangaea led to the origin of oceans and continents. This is supported by scientific evidence and geological studies, which show that the supercontinent Pangaea gradually broke apart around 175-200 million years ago, giving rise to the modern continents and oceans as we know them today. Therefore, A is true.

The Reason (R) states that the disintegration of Pangaea was caused by the forces of gravitation and buoyancy. This is also true. The forces of gravitation and buoyancy play a significant role in tectonic plate movements, which are responsible for the breakup of Pangaea. The movement of tectonic plates is driven by the buoyancy of mantle material and the forces of gravity acting on these plates. Thus, R is true.

Furthermore, R provides a logical explanation for A. The forces of gravitation and buoyancy causing tectonic plate movements explain why Pangaea broke apart, leading to the formation of oceans and continents. Hence, Option 1 is correct.