Development of embryo from the cells of the nucellus is called

Which of the following statements are correct regarding female reproductive cycle?

$A$. In non-primate mammals cyclical changes during reproduction are called oestrus cycle.

$B$. First menstrual cycle begins at puberty and is called menopause.

$C$. Lack of menstruation may be indicative of pregnancy.

$D$. Cyclic menstruation extends between menarche and menopause.

Choose the most appropriate answer from the options given below.

Monoecious plants means.

Which organism do not have heterogametes?

Identify $X$ and $Y$ from the given diagram

Identify the events $(A, B, D$ and $E)$ in life of general reproduction