Answer:
A. calories
Step-by-step explanation:
Calorie can be defined as a standard unit used for the measurement of the amount of energy present in foods and drinks.
Hence, weight gain occurs when a person consumes too much or many calories.
In order to burn unwanted or excess weight (calories), it is very important and essential to engage in aerobic activities.
An aerobic exercise refers to all forms of physical activity that an individual engages in, in order to increase the heart rate (from low to high intensity) in response to the level of oxygen required by any activated or working muscle in the human body.
Some examples of aerobic exercise (cardiofitness activity) includes cycling, swimming, jogging, walking, skiing etc.
Generally, fitness experts usually advises everyone to judiciously engage in cardiofitness activities or exercises so as to improve well-being, body mass index (BMI), wellness or heart health.