a) one student is chosen from classroom a, then a student is chosen from classroom b.
step-by-step explanation:
independent events are ones in which the probability of one event does not affect the probability of the second event.
one student is chosen from classroom a; this does not affect the chances of choosing a student from classroom b. this makes these independent events.
when one card is chosen from a standard deck and then set aside before a second card is chosen, the probability of the second card being chosen changes. this makes them dependent events.
when one student is chosen from classroom a and then a second student is chosen from classroom a, the probability of choosing the second student changes. this makes them dependent events.
when a letter is chosen from the alphabet and then a second letter is chosen, the probability of choosing the second letter changes. this makes them dependent events.