When Is Sam Most Likely to Catch a Cold

When is Sam most likely to catch a cold?

A) when he is exposed to the cold virus and is undergoing a divorce, but he does not find the divorce to be very stressful
B) when he is exposed to the cold virus and recently got a speeding ticket, which was very stressful for him
C) when he is exposed to the cold virus and goes outside on a cold day with wet hair
D) when he is exposed to the cold virus, regardless of what is going on in his life