• Inbreeding Defined: Inbreeding is the mating of individuals that are more closely related to each other by ancestry than the average relationship of individuals within the reference population.
• Genetic Consequences of Inbreeding:
• Increases homozygous genotype frequency ($AA$ and $aa$) while decreasing heterozygosity ($Aa$) at a rate of $F$ (inbreeding coefficient).
• Exposes detrimental recessive alleles, leading to inbreeding depression (reduced fertility, viability, and production).
• Distinctions:
• Pure breeding: Mating of animals within the same established breed.
• Crossbreeding: Mating of animals from two or more distinct pure breeds.
• Outbreeding: Mating of unrelated individuals within a breed (outcrossing) or between breeds.

Correct option: (3) Inbreeding