In a study on the biological bases of learning, lab rat A is given a drug that blocks dopamine activity in its brain. Thereafter, the rat is placed in an operant chamber where a lever-pressing task is shaped through positive reinforcement.
We should expect that the rat will have .

We should expect that the rat will have more difficulty learning the task than a regular rat.

Explanation:

Dopamine plays various roles on the brain, such as enhancing the executive functions, playing a role on motivation, pleasure and gratification. It is the reward system, meaning that it plays a big role in getting an individual to do something because of the reward he/she gets from it, thus motivating the individual.

In this case, we can conclude that the rat with the blocked dopamine activity will have more difficulty learning the lever-pressing task because it loses its reward system and its motivation to do so.

the answer there would be genocide.