Final answer:
The number of students in a class involves the measurement of a discrete variable.
Step-by-step explanation:
The measurement of a discrete variable refers to the process of measuring a variable that can only take on specific, separate values. Out of the options given, the number of students in a class involves the measurement of a discrete variable. This is because the number of students can only be whole numbers and cannot take on any values in between. For example, a class can have 20 students or 21 students, but it cannot have 20.5 students.