Correct Answer: kit

Solution : Given:
1. stars moon sun satellite planet ⇒ pit rit kit sit nit,
2. moon mars venus mercury ⇒ mit cit git sit
3. venus stars mercury ⇒ cit git rit
4. mercury satellite planet ⇒ pit cit nit

By comparing all the four coded sentences, we find that –
In sentences 1 and 2, moon and sit are common.
In sentences 1 and 3, stars and rit are common.
In sentences 2 and 3, venus and git are common.
In sentences 2, 3, and 4, mercury and cit are common.
The remaining words and codes in sentence 1 are satellite/planet and pit/nit , sun, and kit ; in sentence 2 mars and mit.
Finally, stars ⇒ rit; moon ⇒ sit; venus ⇒ git; mercury ⇒ cit; sun ⇒ kit; satellite/planet ⇒ pit/nit

So, with sun will be coded as kit . Hence, the first option is correct.