Students guess that Norb\textquotesingle 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? ($$2011$$ AMC $$8$$ problem, Question \#$$21$$) 
选项为:A:$$29$$  B:$$31$$  C:$$37$$  D:$$43$$  E:$$48$$  请回答其中一个选项.