Answer:Of the ones mentioned here, I'd say that 3, redefine addition, is the easiest way to use and work with to get lots of self consistent theories that have 2 + 2 = 5.
Explanation:
First, it’s easy to prove that 2 + 2 =4. You just need the rule x + Sy = S(x + y) where Sx means the successor of x, or x + 1. With some more steps, with simple natural axioms, you can also derive a contradiction from 2 + 2 = 5. Proof indented so it’s easy to skip.