Correct option is A
In this questions codes are related to their respective digit in the code so direct coding will take place here.
According to Question we have :
G | R | E | A | T |
2 | 4 | 6 | 3 | 1 |
Similarly for
M | O | N | K |
5 | 8 | 9 | 7 |
From this code for 84712 we have =ORKTG