Statement (A) : The first shell is represented by the letter K. 

Statement (B): The second shell L contains 8 electrons. 

Statement (C) : In the fourth shell N, four sub shells are present

According to Niles Bohr , the shells or orbits of an atom are represented by the letters K,L,M,N …… Here, Kshell means 1^st shell, L shell means 2^nd shell and N shell means 4^th shell. The number of electrons present in each shell is equal to 2n² . For , L shell n = 2 ;therefore, it contains  2 (2)2  = 8 electrons.