Right. The normal way we see it written here, like with the CAP theorem, would be:

  CA~P + C~AP + ~CAP

The way it's normally phrased would be: choose 2 of the 3 that you want, the other will be absent from your system. The alternate phrasing would be: choose 1 of the 3 that you can sacrifice, the others will be present in your system. But both phrasings describe the same logical expression written above.

For the right arm, left arm, leg example it's similar. You're being asked which one you would sacrifice so it could be written as:

  RA LA ~L + RA ~LA L + ~RA LA L

Offering two phrasings: which do you want to keep or which will you give up?