Correct Answer: 8

Solution : Given:
1. 481 means sky is blue
2. 246 means sea is deep
3. 698 means sea looks blue

By comparing all the three coded sentences, we find that –
In sentences 1 and 2, is and 4 are common.
In sentences 2 and 3, sea and 6 are common.
In sentences 1 and 3, blue and 8 are common.
The remaining word and code in sentence 1 are sky and 1 ; in sentence 2 are deep and 2 ; in sentence 3 are looks and 9 .
Finally, is ⇒ 4 ; sea ⇒ 6 ; blue ⇒ 8 ; sky ⇒ 1 ; deep ⇒ 2 ; looks ⇒ 9

So, the code for blue is 8. Hence, the first option is correct.