In a mixed letter coding system, if the word 'CAT' is coded as 'XZY', and 'DOG' is coded as 'ABC', what is the code for 'AT' if 'A' is coded as 'X' and 'T' is coded as 'Y'?
Answer: A. XY
The code for 'A' is 'X' and for 'T' is 'Y', thus 'AT' is coded as 'XY'.