Answer:
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, <u>para</u> 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.
