Recuerde del sistema después de usar una computadora pública. entrar
salir
utilizar
usar

The correct option that fills the blank is:

- Recuerde salir del sistema después de usar una computadora pública.

Explanation:

The translation of the sentence is:

- Remember to leave the system after using a public computer.

And the translation of the options is:

In this digital age, an usual recommendation is that if a person uses a public computer, after entering their social networks, closed systems or email, they must leave these networks by means of "logout", since otherwise the next person Using such a computer can modify and even extract information, by this reason, the right option is "salir".

this question is given using the conditional form. conditional tenses are is used when talking about hypothetical situations and probabilities. also, this is used when making polite requests. so comprarías is the conjugation of the verb comprar that matches the second person singular in the conditional. finally:

¿cuál comprarías tú?