I am a bit confused about this question, can someone help please!

What is unusual about a case involving res ipsa loquitor?
A. The defendant assumes the burden of proof.
B. The injury is usually caused by the plaintiff.
C. An injury results even though no negligence is involved.
D. The defendant has no control in the injury.

It must be A.

Check this definition.

http://www.lectlaw.com/def2/q035.htm