In artificial selection, individuals without desirable traits may be prevented from mating by

Analyze the question: Artificial selection (selective breeding) is when humans choose which organisms reproduce, so that offspring inherit desirable traits. The question asks how individuals without the desirable traits are stopped from mating.

Explain the concept:

• Outbreeding is crossing unrelated individuals to introduce new genes and increase variation. It does not stop any individual from mating.
• Sterilization makes an individual unable to reproduce, for example by castrating male animals. It is a direct way to keep unwanted individuals from passing on their traits.
• Inbreeding is mating closely related individuals to keep or fix certain traits. It does not prevent the poor performers from mating.
• Genetic engineering is the direct manipulation of genes, for example inserting a gene into an organism. It is not a method of preventing mating.

Solution: Farmers and breeders want only the best animals or plants (high milk yield, fast growth, disease resistance) to reproduce. To remove the others from the breeding pool, they can:

1. Separate them from the breeding stock, or
2. Sterilize or castrate them.

Of the options, only sterilization actually prevents mating or reproduction by the undesirable individuals.

Answer: B. Sterilization

Exam tip: Remember that inbreeding and outbreeding are breeding methods used on the selected individuals. The word "prevented" points to a method of stopping reproduction, and that is sterilization (or culling or isolation).