In a coded language, 'CAT' is coded as '312', 'DOG' as '415', and 'BAT' as '213'. What is the code for 'TAD'?

Answer: B. 321
The common letters in 'BAT' and 'CAT' help deduce that 'T' is coded as '1', 'A' as '2', and 'D' as '3'. Thus, 'TAD' is coded as '321'.