Appoint and nominate are both verbs that refer to the act of selecting someone for a position or task. However, appoint carries the connotation of giving someone a specific job or task to do, while nominate is more about suggesting someone for a position or award.

To nominate is to propose a candidate for election by shareholder vote, or for direct approval and selection by a board of directors. An appointment does not require any approval or voting. Those empowered to appoint simply exercise it.

In the case of C, however, "nominate" and "appoint" are interchangeable in legal terminology. Your appointing or nominating an executor in your will, or nominating or appointing someone to make crucial decisions about your health if you are unable to do so, indeed are the same thing.

Consider this case of using the words ‘nominate’ and ‘appoint’. To nominate can simply mean to suggest the name as a candidate for a position or job. If there are more than one nominees, one of them will have to be eventually appointed through the appropriate official proceedings.

Elect, as distinguished from nominate, implies a final selection (as by the electorate) from the candidates who have been previously nominated. Appoint always implies that the selection is determined without a general vote (as of an electorate) and represents the choice of the person or the body in whom such power is legally vested.