Filing for a LLC partnership

Hi, I started an LLC partnership on 2021 and started selling online Nov 2021.  However I while going through the wizard I realized that LLC is due March 15 and not April.  2 questions.

1. So now I guess I have to file an extenstion? 

2. when I click on yes tt is asking "reason for short year" so I'm really confused about which options to chose from? 

there is "initial return", final return, and 2 other that for sure its not my situation.  I don't know what these mean but suspect that it A, initial return? 

 

thanks in advance.