In Pavlov's classic experiments, the repeated presentations of the metronome along with the food was called the step of the classical conditioning process.

acquisition                                                        

Explanation:

Acquisition: In psychology, the term "acquisition" was explained by a psychologist named Ivan Pavlov and is defined as the very first stage related to learning in the classical conditioning process through which a specific response is being established.

In other words, the acquisition is described as a period whereby a particular stimulus tends to trigger a specific conditioned response.

Example: In classical conditioning, when a dog begins to salivate after getting associated with the sound of a bell.

In the question above, the given statement signifies the "acquisition" period.