Which of the following is true about studies that ask participant to place a hand in a tub of freezing water, which can cause some discomfort or even pain?

A) This practice is classified as a physical risk.
B) Studies using this procedure are unethical.
C) Stress and pain from this procedure is typically short term and can be an acceptable risk.
D) Studies which cause pain are always acceptable.

Answer: C
Rationale: Making subjects voluntarily submerge their hand in freezing water can be ethically used when participants engage with fully informed consent and know they can stop the procedure at any time. While it can cause physical and psychological stress, this tends to be short term. Therefore, the benefits of a study must be weighed against the risk to participants.