Hello there, and thank you for posting your question here on brainly.
It's almost like a comma but also like a period, that's why it has a period and a comma. You wouldn't start a sentence with the word 'and' would you? So it can't be the third option. It also can't be the first option because you can't do a comma before the word so.
The answer is the second option.
Hope this helped!! ☺♥
