One advantage of using laboratory studies to test the accuracy of the polygraph is that __________; ...

One advantage of using laboratory studies to test the accuracy of the polygraph is that __________; one disadvantage is __________ as compared to field studies.
a. you have better control over the variables; ground truth cannot be established
b. ground truth is known; the motivational level of the subject
c. you can randomly assign subjects to innocent and guilty conditions; you have more control over the variables
d. university students are used; the motivational level of the subject
e. you can randomly assign subjects to innocent and guilty conditions; it is unethical