Well, I'm not sure about how many cells we have, but the average human body makes about 259 billion red blood cells per day. (That's why I don't know). Also, there are about 200 different types of cells with about 20 different types of organelles.
Hope this helps!
To start off a is something you should not even think of doing because you can die, for b that's not a good spot as in there can be extra skin coming from the chin, for c you are getting close but as your neck goes to your torso it gets bigger, D is the correct answer as you would get the most accurate measurement its not to close to the chin or your torso.<span />
Cus it’s red muhahaha hhhhh