A researcher plans to identify each participant in a certain medical experiment with a code consisting of either a single letter or a pair of distinct letters written in alphabetical order. What is the least number of letters that can be used if there are 12 participants,and each participant is to receive a different code?
(A) 4
(B) 5
(c) 6
(D) 7
(E) 8
OA: 5
(A) 4
(B) 5
(c) 6
(D) 7
(E) 8
OA: 5
You can, for example never foretell what any one man will do, but you can say with precision what an average number will be up to!
