A Headwaiter at a Restaurant Decides to Apply the Exclusion

A headwaiter at a restaurant decides to apply the exclusion principle to the seating of patrons. He will treat tables as sub-shells, and will only seat patrons if the number of the people to be seated adds up to a complete sub-shell. Of the numbers below, the number he would not be willing to seat at one table is

A) 2.
B) 4.
C) 6.
D) 10.
E) 14.