Ateacher discusses a scientific theory that has been in place for almost a century. which would present the greatest challenge to this theory?

The theory might have become Obsolete or Superseded

Explanation:

A theory becomes obsolete or superseded if it becomes inadequate, false or incomplete in how its describes reality. It does not matter if it was once accepted. There are some theories such as Lysenkoism that are currently described as being obsolete because it does not conform to current reality. Another example of a theory that was superseded is the phlogiston theory. It was replaced a different theory of energy.