Correct Answer: 3

Solution : Given:
1. he is my friend ⇒ 5692
2. my aunt is ill ⇒ 7635
3. friend is ill ⇒ 627

By comparing all the above-coded sentences, we find that –
In sentences 1 and 2, my and 5 are common.
In sentences 1 and 3, friend and 2 are common.
In sentences 1, 2, and 3, is and 6 are common.
In sentences 2 and 3, ill and 7 are common.
The common words and the codes in sentence 1 are he and 9 ; in sentence 2 are aunt and 3
Finally, my ⇒ 5; friend ⇒ 2; is ⇒ 6; ill ⇒ 7; he ⇒ 9; aunt ⇒ 3

So, aunt will be coded as 3 . Hence, the third option is correct.