For each variable, decide if it is continuous or discrete:
a. The depth, in inches, a person can drive a 3″ nail with one hammer blow

b. The number of students in a classroom who are absent for at least one day during the month of February
c. The total number of days that students in a classroom are absent during the month of February
d. How many friends one has on Facebook
e. The amount of time, measured in seconds, that a person in a driving simulator keeps his or her eyes on the road while engaging in a cell phone conversation