.What other suggested theories have been discredited? Why?

Explanation:

In some cases, a theory or idea is found baseless and is simply discarded. For example, the phlogiston theory was entirely replaced by the quite different concept of energy and related laws. In other cases an existing theory is replaced by a new theory that retains significant elements of the earlier theory; in these cases, the older theory is often still useful for many purposes and may be more easily understood than the complete theory and lead to simpler calculations. An example of this is the use of Newtonian physics, which differs from the currently accepted relativistic physics by a factor that is negligibly small at velocities much lower than that of light.

the answer is c.

i hope this .