Correct Answer: he : 8

Solution : Given:
1. you must study ⇒ 531
2. he must work ⇒ 718
3. work is worship ⇒ 894
4. work is fine ⇒ 864

By comparing all the above-coded sentences, we find that –
In sentences 1 and 2, must is a common word and 1 is a common code.
In sentences 2, 3, and 4, work is a common word and 8 is a common code.
In sentences 3 and 4, is is a common word and 4 is a common code.

So, the word and code in the above sentences –
must→1; work→8; is→4; you/study→5/3; he→7; worship→9; fine→6

So, he: 8 is NOT a correct combination of a word and its code in that language. Hence, the third option is correct.