As a guide, I would recommend the following biology books for Class 12 students:

1. NCERT Biology Textbook: This is the official textbook recommended by the CBSE board and covers all the topics in detail. It is easy to understand, has clear explanations, and contains several diagrams and illustrations to aid in learning.

2. Biology by Campbell and Reece: This book is a comprehensive guide to biology and covers all the topics in detail. It is well-organized, easy to read, and contains several practice questions and exercises to test your understanding.

3. Biology by Sylvia Mader: This book is another popular choice among students and covers all the topics in detail. It is written in a clear and concise manner, with several examples and illustrations to aid in understanding.

4. Biology by Raven and Johnson: This book is a comprehensive guide to biology and covers all the topics in detail. It is well-organized, easy to read, and contains several practice questions and exercises to test your understanding.

5. Biology by P.C. Verma: This book is a popular choice among students and covers all the topics in detail. It is written in a clear and concise manner, with several examples and illustrations to aid in understanding.

In summary, these are some of the best biology books that Class 12 students can refer to for their studies. All of these books are comprehensive, easy to read, and contain several practice questions and exercises to test your understanding.