For each variable, decide if it is discrete or continuous:
a. The number of cases of flu diagnosed at a college in a given semester
b. The size, in grams, of a rat’s hypothalamus

c. The number of teachers, including substitutes, in a school district who are certified to teach high school math
d. The number of times that a rat pushes a lever in a Skinner box during a 15 minute period
e. How long, in seconds, it takes applause to die down at the end of a school assembly