A Valid Statistical Association in Any Analytic Study Design Requires

A valid statistical association in any analytic study design requires consideration of confounding. Which of the following best describes confounding?

A) When an extrinsic factor influences the disease outcome and may or may not influence the exposure
B) When the exposure variable influences the extrinsic factor, which then influences the disease outcome
C) When an extrinsic factor influences the disease outcome and, independent of that relationship, also influences the exposure
D) When an exposure and disease outcome are related