The correct option is C bpxg
From 1st and 2nd statements, the common alphabet is 'O' and the common coded letter is 'b'.
From 2nd, 4th, 8th, 9th, 10th and 12th statements, the common alphabet is 'I' and the common coded letter is 'p'.
From 3rd, 7th and 12th statements, the common alphabet is 'L' and the common coded letter is 'g'.
From 1st, 5th, 6th, 8th, 9th, 10th and 12th statements, the common alphabet is 'R' and the common coded letter is 'w'.
From 5th and 9th statements, the common alphabets are 'RT' and the common coded letter are 'wx' respectively. So, 'x' stands for 'T'.
Therefore, the word 'TOIL' is coded as 'xbpg' or 'bpxg' in any order.
Hence, option (C) is the correct answer.