Which of the following terms relates to menstruation?

The term that specifically relates to menstruation is "Men/o." This root comes from the Greek word "mēn" which means month, and it is used to denote the menstrual cycle, which is often referred to as the monthly cycle in human females. Therefore, "Men/o" is directly linked to menstrual activities and processes, such as menstruation itself and associated conditions.

In contrast, "Metr/o" refers to the uterus but is not specifically tied to menstruation; it can refer to measurement or the uterine structure more generally. "Mening/o" pertains to the meninges, the protective membranes covering the brain and spinal cord, which is unrelated to menstrual processes. "Mental/o" relates to the mind and cognitive functions, further distancing it from the subject of menstruation. Thus, "Men/o" stands out as the accurate term in this context.