Evidence related to which of the following earlier ideas led to the modern theory of plate tectonics?
a continental drift and seafloor spreading
b the big bang theory and natural selection
c seafloor spreading and atomic theory
d biological evolution and the big bang theory

Option (A)

Explanation:

The evidences that led to the plate tectonic theory are as follows-

(a) Continental drift-  Alfred Wegener was the first person to represent this hypothesis that states- the continents were found to be shifting in various directions with respect to a fixed point but the mechanism behind this was not known then. By further studying these continental motions, the main mechanism behind this known.

(b) Seafloor spreading- It was first discovered by Harry Hess and it was the stretching of the seafloor. Due to this, the magma comes out to the ocean floor. This theory helped in understanding the concept of continental drift.

Thus, these 2 pieces of evidence were the first step that led to the theory of plate tectonics. According to this theory, the crust of the earth is composed of lithospheric plates, that move over the asthenosphere layer due to the creation of convection current in the mantle.

Thus, the correct answer is option (A).