Explain it
Correct Option: C
Following the common explanation, we can say that if ‘What A Day’ is coded as ‘de su da’ this means ‘What’ must be coded as ‘de’ and ‘Day’ must be coded as ‘Da’. So, we can say that the code of ‘Good’ is ‘ku’.

Thus, the code for ‘What Good King’ may be ‘ke de ku’.

Hence, the correct answer is option C.