You train hungry rats that a conditional stimulus (CS) predicts delivery of an unconditional stimulus (US). Which of the following procedures is most likely to produce the strongest sign-tracking conditional response (CR)? Group of answer choices CS = light, US = 3 food pellets, CS-US interval 10 seconds, inter-trial interval 100 seconds CS= light, US= 3 food pellets, CS-US interval 2 seconds, inter-trial interval 4 seconds CS = tone, US = 3 food pellets, CS-US interval 10 seconds, inter-trial interval 500 seconds CS= tone, US= 1mA foot shock, CS-US interval 4 seconds, inter-trial interval 100 seconds CS= light, US= 1mA foot shock, CS-US interval 10 seconds, inter-trial interval 1000 seconds CS= light, US= 1 food pellet, CS-US interval 4 seconds, inter-trial interval 20 seconds