Match the followings:
| A. Short Delay | I. The unconditioned stimulus (UCS) is presented briefly after the neutral stimulus (NS) starts. |
| B. Trace | II. The neutral stimulus (NS) is presented and removed before the unconditioned stimulus (UCS) is introduced. |
| C. Backward | III. The unconditioned stimulus (UCS) is presented before the neutral stimulus (NS). |
| D. Simultaneous | IV. The neutral stimulus (NS) and the unconditioned stimulus (UCS) are presented at the same time. |
1
A-I, B-II, C-III, D-IV
2
A-II, B-III, C-I, D-IV
3
A-III, B-IV, C-I, D-II
4
A-IV, B-II, C-III, D-I