According to the Rescorla-Wagner model, an increase in the association between the CS and US occurs when:

A. the prediction error is zero.
B. an unexpected US follows a CS.
C. the prediction error is negative.
D. a predicted US follows a CS.

B. an unexpected US follows a CS.

Explanation: Rescorla-Wagner model is a classical conditioning model which tries to establish a the relationship or association between the CONDITIONED STIMULI (CS) AND THE UNCONDITIONED STIMULI.

According to the Rescorla-Wagner model, proves that for learning to occur the subject must be surprised which means the subject must not expect it(AN UNEXPECTED US FOLLOWS A CS).

d - failures.

the only attempted british colony in north america before 1600 was roanoke, virginia, which was a total failure. england claimed several areas, including newfoundland, but made no sustainable attempts to colonize them before 1600.