L'endroit où on peut acheter des médicaments est un/une

The question asks for the place where one can buy medicines (des médicaments). In French, the word for the establishment that sells medicines is la pharmacie (the pharmacy).

The other options refer to different types of places: l'hôpital is a hospital, where patients receive medical treatment but do not purchase medicines over the counter; la banque is a bank, a financial institution; and l'école is a school, an educational institution. None of these is a place specifically designated for the sale of medicines.

In French vocabulary related to places and services, it is important to associate each establishment with its primary function: la pharmacie sells medicines, la boulangerie sells bread, la boucherie sells meat, and so on.