The incident that started the sepoy rebellion was related to a rumor about the

a. the working conditions at trading posts.
b. the working conditions in textile factories.
c. the materials used to make rifle cartridges.
d. the materials used to sew soldiers’ uniforms.

The answer is C) The materials used to make rifles. The incident that started the Sepoy Rebellion was related to a rumor about the materials used to make rifles. It was rumored that the rifle cartridges were being made from cow and pig fat. This was an issue because of the Indian Sepoy's religious beliefs. The Sepoy's were Hindus and the cow is considered a holy animal to Hindus . It was due to the Sepoy's beliefs and the rumor that violated their beliefs that the Sepoy Rebellion was started.  

definitely a for sure. ill see and update if i get the answer

must repent and believe in god.

or the book

journey across time - chapter 10 "the rise of christianity"