Right answer:
sobre
This word is a preposition and translates into on that means physically in contact with and supported by a surface. Recall that in both Spanish and English a preposition is a word that governs and usually precedes a noun or pronoun and expresses a relation to another word or element in the clause. Examples of preposition in English are at, in, on, etc and in Spanish are en, sobre, etc
So IN SPANISH
Hay una mochila sobre la mesa
IN ENGLISH:
There is a backpack on the table
