Change the drop down values, based on selection in other columns(drop downs)

I am trying to create a template for Risk Analysis Matrix. I have 3 drop downs in 3 columns, Column A Called "Risk Severity" with values (ACCEPTABLE, TOLERABLE,UNDESIRABLE,INTOLERABLE). Column B called "Risk Likelihood" with values (IMPROBABLE,POSSIBLE,PROBABLE) and my last column C is a drop down with "Risk Level" with values (LOW,MEDIUM,HIGH,EXTREME). What I want is based on the selection the user makes in column A"Risk Severity" and Column B "Risk Liklihood" to change the value in column C drop down.

For E.g If A = Acceptable and B= Improbable then C should be Low. If A = Acceptable and B= Possible then C should be Low IF A = Intolerable and B= Probable then C should be extreme so on and so forth.

All in all I will end up with 12 combinations(4*3) and 4 different values in column C based on those 12 combinations.

Thanks in advance for your help