Define:
$(a)$ Juvenile phase,
$(b)$ Reproductive phase,
$(c)$ Senescent phase.

(N/A) Juvenile phase:
It is the period of growth in an individual organism after its birth and before it reaches reproductive maturity.
$(b)$ Reproductive phase:
It is the period when an individual organism is capable of sexual reproduction.
$(c)$ Senescent phase:
It is the final stage of the life cycle,characterized by the onset of aging and the loss of reproductive ability.