Doing side work no LLC - what to do on W9 form?

Question

I am doing some work for on the side for my former employer. They pay me via an application called square that I use.

Its the end of the year so I asked them for a 1099 / W2 and they sent me a W9 form to fill out.

At the top of the W9 is this:

Its section 3 asking for a classification. As this is not really a business, I'm just doing work as a contractor what do I enter here? Do I simply select "Other" and if so do I need to enter in anything? I ask because I am already working at my current full time job at a different company. I am only helping my prior company out and they are paying me via the square application (which is basically via credit card). I charge an extra fee since it is basically credit card as square is charging me fees when I do this so it makes up for the fees.

What do I enter here if this is not really a corporation / trust or an LLC? You can read this thread that I posted from prior asking a question when I first started helping them:

How to handle taxes by using credit card app (Square)

Answer 1

Doing work is "a business" even if you do it under your own name.

The default category if you haven't done any paperwork to form a company is "individual/sole proprietor".

Both terms fit doing work under your own name, depending on whether you look as the contractor as yourself (an individual) or as a small business entity whose sole proprietor is you.