You are going to conduct an experiment to determine which of four different brands of
dog food promotes growth best in puppies ages four months to one year. You are concerned that the effect might vary by the breed of the dog, so you divide the dogs into five different categories of breed. This gives you eight dogs in each category. You randomly assign two of the dogs in each category to one of the four foods. The design of this study is best described as:

Question

You are going to conduct an experiment to determine which of four different brands of 
dog food promotes growth best in puppies ages four months to one year. You are concerned that the effect might vary by the breed of the dog, so you divide the dogs into five different categories of breed. This gives you eight dogs in each category. You randomly assign two of the dogs in each category to one of the four foods. The design of this study is best described as:

anonymous · Answer

A.Randomized block, blocked by breed of dog and type of dog food.
B.Randomized block, blocked by type of dog food.
C.Matched pairs, with each two dogs considered a pair
D.Randomized block, blocked by breed of dog.
E.A controlled design in which the various breed of dogs are the controls.

anonymous · Answer

I think it's A.