Assertion : Protandry and protogyny ensures cross fertilization.
Reason : Cross fertilization introduces variation in progeny.

If both assertion and reason are true and reason is the correct explanation of assertion

If both assertion and reason are true but reason is not the correct explanation of assertion

If assertion is true but reason is false

If both assertion and reason are false

Solution

If both assertion and reason are true but reason is not the correct explanation of assertion

In some lower animals, the organs of both the sexes are found in the same individual. Hence, they are called bisexual or monoecious animals or hermaphrodites. In these animals, testes and ovaries do not mature simultaneously.

For example in earthworm, testes mature earlier, while in others, e.g., sea-squirt, ovaries mature earlier. These conditions are respectively called protandry and protogyny. They ensure cross fertilization.

Cross fertilization is a process in which gametes derived from different individuals are united to form zygote. It involves the mixing of two different genetic materials. This is better than self-fertilization as it introduces variation by combining traits of two individuals.