What must be done to breed dogs for a particular trait?

a. Mate two dogs that have the desired trait.

b. Protect dogs with the trait from natural selection.

c. Mate any dogs and see what variations occur.

d. Place dogs in places where they can acquire the trait.

The answer is A because the question is asking for a particular trait and answer A says desired trait which is a synonym for particular trait.

Well a and b are eliminated instantly due to the fact of that you're trying to find the trait and in a and b you already have found it. So you have c and d and placing dogs in places to see if they get the trait can go wrong at any time due to the partner or certain genes. I would stick with c.