Correct Answer: 4965

Solution : Given:
1. read this book ⇒ 689
2. this book is useful ⇒ 9675
3. useful book is good ⇒ 5479

By comparing all the above coded sentences, we find that –
In sentences 1, and 2, this and book are the common words and 6 and 9 are the common codes.
In sentences 2 and 3, useful, is and book are the common words, and 5, 7, and 9 are the common codes.
The remaining words and the code in sentence 1 are read and 8 , in sentence 3 are good , and 4 .

So, this book is good will be coded as 4965 . Hence, the first option is correct.