On the first day of class, Professor Bigelow tells her geography students that pop quizzes will be given at unpredictable times throughout the semester. Clearly, studying for Professor Bigelow's surprise quizzes will be reinforced on a schedule.

B. Variable Interval

Explanation:

The variable interval schedule is the schedule in which the schedule is not fixed with regard to anything that means anything can be happen at any time

there is no fixed time

Since in the question it is mentioned that the Professor Bigelow told her students that the quizzes would be provided at non-predictable times so here the surprise quizzes would be reinforced on a variable interval schedule

Therefore the correct option is b.

answer; ///i believe that the correct answer is (d) when each house of congress passes a different version of a bill and those difference must be

c. taught scientists many new things about the earth, but not other planets.

explanation: