because of the "likely" in the question, I would say C (three years old)
but this question is very subjective. Children have their own progresses and can't be compared.....
Some are walking at 12 months, some at eighteen months, same for speaking !
Answer:
lack of energy and motivation to keep them up during the day. There also might be a constant feeling of tiredness as some people tend to fall asleep/ get tired after exercising.
if muscles are not used on a regular basis they become weak and less flexible, the way to offset this effect is to exercise more often.
