Correct Answer: PAINTER

Solution : Given:
CARPENTER

Now, let's compare all the option words with the word CARPENTER –
First option: NECTAR; All the letters of NECTAR are present in the word CARPENTER.
Second option: CARPET; All the letters of CARPET are present in the word CARPENTER.
Third option: PAINTER; All the letters of PAINTER are not present in the word CARPENTER. I is not present in the word CARPENTER.
Fourth option: REPENT; All the letters of REPENT are present in the word CARPENTER.

So, from the above, only PAINTER cannot be formed using the letters of the word CARPENTER. Hence, the third option is correct.