Question

Julio: ¿Qué me aconsejas usar para proteger mis ojos del sol?
Alberto: Es aconsejable que ____________ gafas de sol.

usa

usas

usar

uses

Answer 1

Uses

Answer 2

You need the subjunctive in this case.
Sometimes it's easier to think of the subjunctive after the word "que" because it appears often in sentences that way.
que yo use
que tú uses
que el use
que nosotros usemos
que vosotros uséis
que ellos usen