Answer:
A = {MOPN, MPON, PMON, POMN}
Step-by-step explanation:
Everybody has already decided that Naim is the last skater, so we need to make sure the result is 'N' in each last position. As we can see all of them have this.
However, we just need to make sure that Oliver doesn't first, because even if they're attempting to decide, the question is calling for the inclusion in which "Oliver is the very first skater in the race."
A complement is all the NOT values in the package or set, so it cannot be either A = {OPMN, OMPN) or A = {MOPN,MPON, OPMN, POMN), since all of them have at minimum one case where 'O' is first.
A complement is ALL other values of the set, and it can not be A = {MOPN, PMON}, since only two possible values are included in that package or set
