If it were me, I'd make a little table elsewhere and use it as a
lookup. 2 columns:

Column AA:
HighYesHigh
HighYesMed
HighYesLow
MedYesHigh

....and so forth for all 18. No spaces.

Column AB would have the appropriate values for each choice.

Column D would have a simple formula:
=VLOOKUP(A1&B1&C1,$AA$1:$AB$18,2,FALSE)