The correct option is A S218OC30X
From the example given ,
PANCAKE = Q2OD2L10
The code can be deduced as
1, If the letter is a consonant replace it by the next letter in alphabetical order.
2, if the letter is a vowel, multiply the numerical equivalent of that letter by 2 and replace the letter with it
Following the code
RAINBOW can be coded as
RAINBOW = S218OC30X