Final answer:
The code for 'nest' in the given language is 14151920 (option A).
Step-by-step explanation:
To find the code for the word 'nest' in the given code language, we need to break down the word and assign corresponding numbers to each letter. Let's do that:
n → 14
e → 5
s → 19
t → 20
So, the code for 'nest' in the given language is 14151920, which is option A.