Which of the following is a correct mode of reproduction?

One of the following is not a method of asexual reproduction:

What is maintained through reproduction from generation to generation?

Select the correct option for external fertilization.

Reproduction without the fusion of gametes $- P$
Reproduction involving the fusion of gametes $- Q$
Choose the correct option for $P$ and $Q$.
$\quad\quad \quad P \quad\quad\quad \quad Q$

Distinguish between asexual and sexual reproduction. Why is vegetative reproduction also considered as a type of asexual reproduction?