Answer:
Variable Interval.
Explanation:
Veronica has a very generous boss who occasionally brings in gift cards for his workers. He does this for no particular reason; it is just a nice way to keep people motivated. Veronica never knows when she is going to get a special bonus from her boss. Veronica's boss is reinforcing his workers according to a variable interval schedule. Variable interval schedule is a kind of operant conditioning reinforcement where reinforcement is being applied and substituted after a particular time but this time is variable, changing, unknown and unpredictable.
