B1 or B2 visa for my friend *and* business partner

[inmiquestions535]

Hi all,

I would like to take my friend (who is also my business partner) to the US to participate in a volunteer project this summer related to our tourism project here in South America (learning bio-construction techniques and applying them to our business here) which would include some travel time and additional time to visit with my family.

Would it be best for him to apply for a B1 or B2 visa?

Thanks for your help!

[immihelp]

Each person would have to apply for visa separately and each person would be evaluated independently.