When using science to investigate physical phenomena, which characteristic of the event must exist?
predictable
observable
provable
readable

The answer is:

When using science to investigate physical phenomena, observable  must exist.

The explanation:

In physics, an observable is a dynamic variable that can be measured. Examples include position and momentum. ... In quantum physics, it is an operator, or gauge, where the property of the system state can be determined by some sequence of physical operations.

the order for strong to weak forces such as

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force

the fundamental forces are those forces that act between to objects or element to make interactions. there are four types of fundamental forces such as strong and weak nuclear forces (due to protons and electrons), electromagnetic force (due to the motion of electrons) and gravitational force (due to orbital movement of the planet). if these forces are arranged on the basis of their maximum strength then the order is

strong nuclear force → electromegnetic force → weak nuclear force → gravitational force