Which of the Following Statements About Internal Validity Is True

Which of the following statements about internal validity is true?

A) One of the most important threats to internal validity is being unable to generalize findings on a scientific basis.
B) The sophistication of the statistical test we employ is a major indicator of the extent that threats to internal validity exist in our situation.
C) The better our sampling method, the more we need to be concerned with threats to internal validity.
D) When we speak of threats to internal validity, we are speaking of probabilities, not possibilities.