Inbreeding is defined as which of the following?

• A. Breeding related animals to one another
• B. Crossbreeding to combine traits from different breeds
• C. Outcrossing to unrelated individuals
• D. Hybrid vigor achievement through crossing species

Answer: (A)

Inbreeding means breeding related animals to one another. When relatives mate, their offspring are more likely to inherit identical copies of genes from a common ancestor, which increases homozygosity in the population. This can help fix desirable traits within a line, but it also raises the chance that recessive deleterious alleles are expressed, potentially reducing health and vigor. The other options describe different breeding approaches: crossbreeding combines traits from different breeds and typically uses unrelated lines; outcrossing involves unrelated individuals to increase heterozygosity; and achieving hybrid vigor through crossing different species refers to interspecific or distant crosses, not inbreeding.