The period of life, when the body undergoes changes, leading to reproductive maturity, is called adolescence.

Introduction:
The period of maturity of reproductive organs refers to the stage when the reproductive system becomes fully functional and is able to produce offspring. This stage is known as adolescence.

Adolescence Period:
- Adolescence is a transitional stage between childhood and adulthood.
- It is characterized by rapid physical, psychological, and emotional changes.
- It is during this period that reproductive organs such as the testes in males and the ovaries in females reach maturity.

Physical Changes:
- In males, the testes begin to produce sperm cells, and the production of the male hormone testosterone increases.
- In females, the ovaries start to release mature eggs during ovulation, and the production of the female hormones estrogen and progesterone increases.
- Secondary sexual characteristics such as the growth of pubic hair, development of breasts in females, and deepening of the voice in males also occur during this period.

Psychological and Emotional Changes:
- Adolescents experience changes in their thoughts, feelings, and behaviors.
- They develop a sense of identity and start exploring their sexuality.
- They may experience emotional ups and downs due to hormone fluctuations and the challenges of transitioning into adulthood.

Menstruation:
- Menstruation refers to the monthly shedding of the uterine lining in females.
- It is a part of the menstrual cycle and is a sign of reproductive maturity.
- However, menstruation itself is not the period of maturity of reproductive organs.

Gestation Period:
- The gestation period refers to the time during which a fetus develops within the uterus of a female.
- It is not the period of maturity of reproductive organs but rather the stage of pregnancy.

Conclusion:
The correct answer is option 'A' - Adolescence period. This is the stage when reproductive organs become fully functional, and individuals reach sexual maturity. It is characterized by physical, psychological, and emotional changes that prepare individuals for reproduction.