Answer:
Pues puedes llamar a alquien que sepa abrir puertas y que te abran la puerta
Explanation:
I believe your answer will be 3.
When you're talking about nonspecific things.
it's like (a) and (an) in english.
uno is for singular masculine.
una is for singular feminine.
unos is for plural masculine.
unas is for plural feminine.