Concept:The triceps muscle is attached to the upper part of the ulna at the olecranon process.In the given diagram, this attachment surface is the part labelled III.Explanation:The triceps is a muscle located at the back of the upper arm.It extends the elbow when it contracts.Its lower end is attached to a bony projection of the ulna called the olecranon process.This process provides the surface for the triceps attachment.Among the labelled parts, part III represents this olecranon process.Answer:C. III
