Answer:
Testing a new drug developed for treating degenerative joint disease (DJD) in dogs
The major reason for separate assignment for each breed of dog is that:
E) There must be an equal number of dogs in each of the two treatment groups.
Step-by-step explanation:
One of the two groups is the experimental group (treatment group). It receives the new treatment whose effect the researchers are interested in finding out. The other half (group) is called the control group. It receives the traditional drug. This control group (also called the comparison group) ensures that the treatment the researchers are giving to the dogs causes the expected experimental results. This means that the results of the two groups are compared to determine the different effects.