Determine whether each of the following random variables is discrete or continuous.
a. The number of heads in 100 tosses of a coin.
b. The length of a rod randomly chosen from a day's production.
c. The final exam score of a randomly chosen student from last semester's engineering statistics class.
d. The age of a randomly chosen Colorado School of Mines student.
e. The age that a randomly chosen Colorado School of Mines student will be on his or her next birthday.