Step 1: Understanding sprain.
A sprain is an injury to a ligament (which connects bones) around a joint, typically caused by overstretching or tearing. It most commonly occurs in the ankle, wrist, or knee joints.
Step 2: Analyzing the options.
- (A) Bone: A sprain does not involve bones; fractures are related to bone injuries.
- (B) Muscle: Sprains do not affect muscles; muscle injuries are called strains.
- (C) Joint: Correct! A sprain involves ligaments around the joint.
- (D) None of the above: This is incorrect since option (C) is the correct answer.
Step 3: Conclusion.
Thus, the correct answer is \( \text{(C) Joint} \).