Students guess that Norb's age is 24,28,30,32,36,38,41,44,47, and 49. Norb says, "At least half of you guessed too low, two of you are off by one, and my age is a prime number." How old is Norb?<spanclass=′latex−bold′>(A)</span>29<spanclass=′latex−bold′>(B)</span>31<spanclass=′latex−bold′>(C)</span>37<spanclass=′latex−bold′>(D)</span>43<spanclass=′latex−bold′>(E)</span>48