Answer:
The correct answer is option 3. "anisogamy".
Step-by-step explanation:
Anisogamy, also known as heterogamy, is a form of sexual reproduction that involves the fecundation of gametes of different sizes and shapes. The larger gamete is the female (egg), while the smaller gamete is male (sperm). There are different types of anisogamy, classified according to how big the difference between the sizes of the gametes are, and if the gametes are motile because of being flagellated.