What Is the Difference Between Internal Validity and External Validity

What is the difference between internal validity and external validity?

A) Internal validity deals with accuracy of methods of studying variables, whereas external validity deals with randomization of variables present in the study.
B) Internal validity deals with creation of operational definitions for procedure, whereas external validity deals with establishing curvilinear relationships between variables.
C) Internal validity deals with accuracy of conclusions about cause and effect, whereas external validity deals with generalization of findings of a study to other settings.
D) Internal validity deals with establishing positive linear relationships between variables, whereas external validity deals with establishing negative linear relationships between variables.