Final answer:
The correct answer is A. Circuit training, which is a series of exercises performed with limited rest, incorporating both vigorous and medium intensity workouts.
Step-by-step explanation:
Groups of exercises performed in sequence with limited rest is called circuit training. Circuit training involves a series of exercise stations, where each one is performed for a certain number of repetitions or for a set time before moving quickly to the next exercise.
The pattern described in the question, which includes short periods of vigorous muscular work and longer periods of medium and varied muscular work, aligns with the concept of circuit training and not with the other options provided.