The correct answer is Option 2 : The assertion and reason provided are correct but reason is not the correct explanation of assertion .

Assertion: Menstrual cycle starts only after attaining sexual maturation (puberty). This assertion is generally correct. The menstrual cycle typically begins with the onset of puberty, which is characterized by various physical and hormonal changes, including the onset of menstrual periods in females. Puberty marks the maturation of the reproductive system and the initiation of the menstrual cycle in girls.

Reason: During ovulation, only one ovum is released per menstrual cycle. This reason is also generally correct. During a menstrual cycle, typically only one ovum (egg) is released from the ovary during ovulation. However, in some cases, multiple eggs can be released during one cycle, especially in instances of hyperovulation, leading to the possibility of fraternal twins or multiple pregnancies.

While both statements are true individually, they are not directly linked. The initiation of the menstrual cycle with sexual maturation and the release of one ovum during ovulation are two distinct aspects of the female reproductive system. The onset of the menstrual cycle is associated with sexual maturation, but the assertion does not directly relate to the reason given about the number of eggs released during ovulation.