Identify which goal of experimental design (i.e., reducing bias or limiting effects of sampling error) is aided by the following procedures:

a. Including extreme treatment levels.

b. Using a paired design.

c. Keeping room temperature constant in an experiment designed to test the effects of a pesticide on insect survival.

d. Eliminating artifacts when designing the treatment of interest.

e. Adding a sham operation group Identify the particular feature that defines each of the following experimental designs, and list the specific advantages provided by the feature you identify.