During a typical morning, Colin checks the clock frequently (frequency of time) before being reinforced with confirmation that the time for his regularly scheduled lunch break has arrived. In this case, Colin's behavior is reinforced on a schedule."

fixed-interval    

Explanation:

Fixed-interval schedule is considered as one of the four distinct types of reinforcement schedule in the operant conditioning theory which was introduced by B. F. Skinner. A fixed-interval schedule is referred to as a reinforcement schedule whereby the very first or initial response is being rewarded once a 'specified time amount' has been passed or elapsed.

In this case, Colin's behavior is reinforced on a fixed-interval schedule.

d. i assume the underlined word is "role." reformat if it isn't.

explanation:

role is closest to part because when replacing words, "playing a vital decision," "playing a vital activity," and "playing a vital dollar" don't make logical sense. the only meaningful choice is "playing a vital part."

this fits one of merriam-webster's definitions of role: "a function or part performed especially in a particular operation or process."

answer; nonpartisan election;