Necesito el vestido el viernes. b. para
a. por
Please select the best answer from the choices provided

Para

Explanation:

First, let's translate the sentence.

Necesito el vestido el viernes.

--->

I need the dress Friday.

We need to fill in the blank with para or por.

In the sentence, someone needs a dress on a specific day. Basically, it is discussing a deadline. When deadlines are involved, para is used.

So, the sentence will become:

Necesito el vestido para el viernes

-->

I need the dress for Friday  OR I need the dress by Friday.

corras is the only one that is informal but doesn't follow the suffix rule. correr is the verb. corre is the formal verb form. corra would be used as the formal is corre ended with an a.

your best bet would be corras, it's the only one that is informal but is still wrong