What are examples of things that can cause mutations?

Exposure to chemicals.

Explanation:

Mutations arise spontaneously at low frequency owing to the chemical instability of purine and pyrimidine bases and to errors during DNA replication. Natural exposure of an organism to certain environmental factors, such as ultraviolet light and chemical carcinogens (e.g., aflatoxin B1), also can cause mutations. Hope this helped. :D

Here are 3 examples;

Example 1: Sickle-Cell Anemia & Malaria

Example 2: Lactose Tolerance

Example 3:  Klinefelter’s Calicos

Explanation:

stress fractures occur largely in the feet and legs and are common in sports that require repetitive impact, primarily running/jumping sports such as gymnastics or track and field.

i believe the answer is a or 1