Hi @sdelgado and welcome to the Community!
This seems similar to this post: Problem formating formula field - #2 by darragh
If youre field Respuesta 1 - SU is a single option field, then you need to use the internal name, which you can find by putting that value in a formula on it’s own.
In your case it’s probably BAC_1_PLASTICO
It’s upper, snake_case
Open becomes OPEN
Closed becomes CLOSED
Awaiting approval becomes AWAITING_APPROVAL
And so on