Which One of the Following Is a Fundamental Difference Between

Which one of the following is a fundamental difference between competitive and noncompetitive antagonist ?

A) Competitive and non competitive work on different receptors .
B) Competitive antagonist reduces agonist potency (increase EC50) and non competitive antagonist reduces agonist efficacy (decrease E max ) .
C) There is no difference between them , they are exactly the same .
D) Non competitive antagonist causes an upward shift of the E max while competitive antagonist does the opposite .