Final answer:
A nocturnal emission, commonly known as a wet dream, is an involuntary ejaculation during sleep and is a natural part of male puberty. It does not indicate the onset of menarche, which is the first menstrual period in females, nor is it associated with females experiencing stress.
Step-by-step explanation:
A nocturnal emission is a natural occurrence during adolescence marked by the involuntary ejaculation of semen during sleep. This phenomenon is informally known as a 'wet dream', and it typically signifies a developmental milestone in sexual maturity among males. Nocturnal emissions can happen multiple times during puberty, beginning generally around the age of 13.
Regarding the options provided in the question:
- A. is called a wet dream Correct, nocturnal emissions are commonly referred to as wet dreams.
- B. signals the onset of menarche Incorrect, menarche refers to a female's first menstrual cycle, not related to nocturnal emissions.
- C. can occur early in girls in stressful environments Incorrect, nocturnal emissions specifically concern the male reproductive system and are not experienced by females.
- D. occurs in about 30 percent of pubescent boys Incorrect, the occurrence can be common among the majority of males during puberty, not limited to 30 percent.
During puberty, boys and girls experience a series of hormonal changes that lead to sexual maturation. The term 'nocturnal emission' is specifically tied to male puberty and does not directly relate to the menstrual cycle, menarche, or the development of female sexual characteristics.