After the model evokes an imitation, that behavior comes into contact with contingencies of:

The answer is "reinforcement".

The behavior comes into contact with contingencies of reinforcement after the model evokes an imitation. The controlling variable for discriminated operant is the new contingencies of reinforcement.  This situation explains Controlled Relation, which is considered as the most important property that defines imitation between a model and a similar behavior.

Ibelieve that the answer is (a).

Ghana, first of the great medieval trading empires of western africa (fl. 7th–13th century). it was situated between the sahara and the headwaters of the sénégal and niger rivers, in an area that now comprises southeastern mauritania and part of mali.