The correct answer is A. Inbreeding.
Self-pollination is the transfer of pollen from the anther of a flower to the stigma of the same flower. This can happen naturally, when pollen is transferred by wind or insects, or it can be done artificially by humans.
Self-pollination can lead to inbreeding, which is the mating of closely related individuals. Inbreeding can increase the chances of genetic defects in offspring, as the parents share more of the same genes. This can lead to problems such as reduced fertility, increased susceptibility to disease, and birth defects.
Overbreeding is the mating of animals too frequently, which can also lead to genetic defects. Outbreeding is the mating of animals that are not closely related, which can help to reduce the risk of genetic defects. Rare breeding is a term that is not commonly used in biology. It could refer to the mating of animals that are very rare, or it could refer to the mating of animals that are not typically considered to be compatible.
In conclusion, self-pollination can lead to inbreeding, which can increase the chances of genetic defects in offspring.