Fact 1: The Himalayas were formed by rock folding.

Fact 2: Folding A fold is a bend in the rock layers.

Given the two facts above, answer the question "What had to bend to form the Himalayas?" with the following options: 
- bamboo
 - smaller mountains
 - an object
 - light
 - rock layers
 - graptolites
 - four limbs
 - sediment


 

     rock layers    