This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Biochemistry
Frame shift mutation is caused by: 
Select and explain. 
A. Deletion, B. Point mutation, C. Substitution, D. Transversion
A: Deletion
Answer: A: Deletion 
Explanation: Frameshift Mutation:

Due to insertion or deletion of nucleotides that are not a multiple of three results in frameshift mutation.
Reading frame is garbled.

Reference- Harper 30th edition page 417