What is strong? When we initially hear the word most of us think of muscles and bodybuilders. There are so many versions of strong that we need to understand that everyone is strong in their own way. The single mother might have a very low muscle mass but she is a strong provider for her children. What about the drug addict that battles his/her addiction to get back to a normal life. There are endless examples to the word strong.
We can put 10 people on a stage and we can make guesses all day about who we feel is the strongest, but the simple fact is that what makes people strong is how they react to situations that demands them to be strong. It is a measure that there is no scale for, as we cannot compare each strength against another strength because they are all so different. Plus you have to factor in so many variables for each strength it becomes an even more impossible task.
So you might be best able to say that everyone has the possibility to be the strongest person in the world given the right situation.