Which form of investment has the most amount of risk involved?

Is this supposed to be a multiple choice question?  It is way fun to think about projects other people might be up to which carry outrageously high risk!

Restaurants are a common example -- there's a little bit of magic in whether a new restaurant will catch on and become popular.

Farming is pretty risky.  You can do everything right and have a hail storm come and ruin the crops.  That's why there are government programs and commodity markets that help farmers mitigate their risk -- because the rest of us who need to eat really need for people to be willing to farm!

The answer may be c ..