In a mixed letter coding system, if 'TRAIN' is coded as 'UQJRO', and 'PLANE' is coded as 'QMBOF', what is the code for 'AN' based on the given codes?

Answer: A. QO
From 'TRAIN', 'A' is coded as 'Q' and 'N' is coded as 'O', thus 'AN' is coded as 'QO'.