Context: Read the passage and look at the picture.
The Andean Volcanic Belt spans the west coast of South America. This volcanic belt began to form when the Nazca Plate moved toward and subducted, or sank, below the South American Plate.
Nineteen of the volcanoes in the Andean Volcanic Zone are in Colombia. Some of these volcanoes, such as the Nevado Del Ruiz volcano, are covered with ice and snow. When Nevado Del Ruiz erupts, the lava melts the ice and snow. This process can form a dangerous mudslide called a lahar.
Complete the sentence.
The Andean Volcanic Belt formed at a () boundary.
A. convergent
B. divergent
C. transform
Identify the correct option from the choices provided and respond with the letter of the correct option.

A