The correct option is A wfsq
From 1st, 5th, 6th, 8th, 9th, 10th and 12th statements, the common alphabet is 'R' and the common coded letter is 'w'.
Again, from 3rd, 5th, 6th, 8th and 11th statements, the common alphabet is 'A' and the common coded letter is 's'. So, 'A' is coded as 's'.
From 8th and 11th statements, the common alphabets are 'AC' and the common coded letters are 'sq' respectively.
So, 'C' is coded as 'q'.
Now, from 1st and 2nd statements, the common alphabet is 'O' and the common coded letter is 'b'.
From 1st, 4th and 7th statements, the common alphabet is 'E' and the common coded letter is 't'.
Clearly, from 1st statement, the code for 'H' is 'f'.
So, code for 'ARCH' is 'swqf' or 'wfsq'.
Hence, option (B) is the correct answer.