Concept:Sexual maturity in farm animals is controlled by internal and external factors such as genetics, sex, and feeding, not by the timing of weaning.Explanation:The breed of an animal affects the age at which it reaches puberty.The sex of the animal also matters, as males and females often mature at different ages.Nutrition greatly influences growth and reproductive development.Weaning age is a management decision and does not directly determine sexual maturity.Answer:D. weaning age