Answer:
Due to similar chemical composition of rocks of both continents.
Step-by-step explanation:
Wegener use the similar mountain ranges and areas as evidence that these two continents i. e. Africa and South America were once connected because of their same chemical composition of rocks. Before 175 million years ago all the continents are joined with each other which we called as supercontinent. Due to this, we can say that Africa and South America is also connected to each other and having same rock chemical composition.