Context: Read the passage and look at the picture.
The Saharan Atlas, a mountain range in northern Africa, began to form millions of years ago as the Eurasian Plate and the African Plate moved toward each other. As the plates collided, the continental crust was forced upward to form tall mountains.
Along the sides of the mountains in the Saharan Atlas, there are riverbeds called wadis. Wadis contain water only during wet seasons. The rest of the year, the river beds are dry.
Complete the sentence.
The Saharan Atlas formed at a () boundary.
A. convergent
B. transform
C. divergent
Answer with the option's letter from the given choices directly.

A