Tommy is frequently asking his parents questions, and they want to decrease his behavior to an acceptable level.Tommy's parents tell him that they will answer a question only if it has been at least 10 minutes since his last question.If Tommy asks a question before the 10-minute interval is up, his parents do not reinforce his behavior with an answer to the question? Which DRL variation are Tommy's parents using?

A) full-session DRL
B) interval DRL
C) spaced-responding DRL
D) secondary DRL