Probiotics are which of the following?
1) microorganisms that live in the digestive tract
2) a dietary supplement made from yogurt
3) a natural medication used in place of antibiotics
4) all of the above

I would say microorganisms that live in the digestive tract. While technically it could be number 2 probiotics aren’t solely in yogurt because they are just nonpathogenic bacteria and for that reason they probably shouldn't be used for number 3. While technically yes bacteria can kill other unicellular bacteria it’s definitely not smart to take some form of bacteria pathogenic or nonpathogenic to fight other bacteria.

the insertion of a penis into a vagina.