To Examine the Internal Validity of a Research Study, Which

To examine the internal validity of a research study, which question does the nurse midwife consider?

A) Was the random sampling of the study participants adequately diverse and truly representative of the identified population?
B) Were the design, methodology and methods sufficiently rigorous and clear-cut to have inhibited extraneous and confounding variables?
C) Could the changes in the outcome of the study be ascribed to alternative reasons or factors that were not explored in the study?
D) Is there clear evidence that the hypothesized observation was actually detected, clearly observed, and measured in the analysis?