Correct Answer: ROUTE

Solution : Given:
COMFORTABLE

Now, let's compare all the option words with the word COMFORTABLE –
First option: FORT; All the letters of FORT are present in the word COMFORTABLE.
Second option: TABLE; All the letters of TABLE are present in the word COMFORTABLE.
Third option: COMFORT; All the letters of COMFORT are present in the word COMFORTABLE.
Fourth option: ROUTE; All the letters of ROUTE are not present in the word COMFORTABLE. U is not present in the word COMFORTABLE.

So, from the above, only ROUTE cannot be formed using the letters of the word COMFORTABLE. Hence, the fourth option is correct.