A researcher wants to test how diets A and B affect the weight loss of rabbits. She has 20 rabbits to use, but all of the rabbits are different sizes, which might affect how much weight they lose. The researcher decides to group the four smallest rabbits in one group, the next four smallest rabbits in another group, etc., until the final group has the four largest rabbits. Then, from each group she randomly selects two rabbits to have diet A, and the remaining rabbits in the groups have diet B.

Select all that apply:
A. This is an example of a block design.
B. This is an example of a completely randomized experiment
C. This is an example of a matched pairs experiment.
D. The treatments are diets A and B.
E. The treatment is how much weight a rabbit loses.
F. The experimental units are the 20 rabbits.
G. The experimental units are diets A and B

A. This is an example of a block design.

D. The treatments are diets A and B.

F. The experimental units are the 20 rabbits.

Explanation:

The randomized block designs are used in experiment when there is only one variable of prime importance but along with it there are several nuisance factors. As in this case, the prime variable is the impact on weight of rabbits when they consume one the given diets. However, several nuisance factors are unequal weights of the rabbit, different class of rabbits, eating habits of rabbit, time of feeding etc.  

Treatment in an experiment is the independent variable that is varied to measure its impact on the subjects of the experiment.  

Here these independent variables are diet type A and B and the subject is the group of 20 rabbits. Subjects are also referred as experimental unit i.e on which the experiment is being conducted

Hence, option A, D and F are correct

parasites can detrimentally affect their host, but also must not allow their host to die before they can complete their life cycle. some parasites have complex life cycles with many different hosts, and have had to find ways of persisting in many different environments during the change from one host to another. ectoparasites live outside the body of the host, and can more easily  disperse, but are  more exposed to predators, parasites, parasitoids. endoparasites live inside the body of the host, and are therefore protected from the outside environment. but they can be  attacked by the host's immune system. they have therefore developed  mechanisms for dispersal such as  complex life cycles.