Scenario Two Researchers Addressed the Generally Accepted Idea That Boxer Shorts

Scenario
Two researchers addressed the generally accepted idea that boxer shorts are better for male fertility than briefs because they lower testicular temperature. They begin by saying, "Although this idea is regarded as dogma by many in the lay community and the changing of underwear type is a therapy frequently recommended by medical practitioners, there is a paucity of data measuring scrotal temperature as a function of underwear type. ("Munkelwitz, Robert, and Gilbert, Bruce R. "Are boxer shorts really better? A critical analysis of the role of underwear type in male subfertility." The Journal of Urology, 160.4 (1998) : 1329-1333.)
-What data besides core, skin, and scrotal temperatures would be good to gather to support or reject the hypothesis that underwear type affects fertility?

A) the size and position of participants' testes
B) the number and quality of sperm in wearers of each type of underwear
C) the ability of participants to maintain temperature in very cold or very warm conditions
D) the fertility of each man's partner