In sociology, individuals change their roles through life as responsabilities, expectations and tasks do not remeain the same during life but evolved at certain age or moments whihc are knwo as age-related transition point. Additionally, these transition points as the process of socialization that implies varies according to the context, culture and time. In the case of the U.S. and many other countries nowadays transition points include the school age becasue in this, the infant or kid is asked to assume his role as student; the adulthood that implies new roles as an independent person and employeed and in elderly a transtion to senior citizen that implies retiring from work and ssuming different roels and responsabilities. However, the infancy is not an age related transition point as this is the first stage in life and during this any important changes in role responsabilities or task are asked in the kid until the school age.
The students in Puerto Rico often reached the schools they are in through walking. So, the answer to the question above is letter A. They do this often as some of the schools are accessible this way. It is also said that walking around towns in Puerto Rico is quite safe.