What happens when two different theories are created for explaining the same thing?

Which metal exist in liquid state and can be cut with knife ?

An engineer decides to use a slightly weaker material rather than a stronger material, since she knows that the stronger material can break suddenly. this is an example of what? a choosing a material that will show warning before it fails b using composite materials that combine strength c using a material for multiple applications d using design techniques that increase efficiency and reduce cost

Introduction of drugs into the gastrointestinal tract is a form of administration. a. enteral b. topical c. parenteral d. inhalation