Yes, you can choose Botany as an optional subject even if you have already chosen Zoology as another optional subject.

Choosing Botany as an optional subject along with Zoology can be a great combination for those who are interested in the study of plants and animals. Both subjects are related to the field of biology and have their own unique areas of focus. Here are some reasons why you can choose Botany as an optional subject along with Zoology:

1. Interdisciplinary Approach:
- Botany and Zoology are closely related subjects and together they provide a comprehensive understanding of the biological world. Studying both subjects will allow you to have a more interdisciplinary approach to the study of living organisms.

2. Overlapping Concepts:
- While Botany primarily deals with the study of plants, there are several concepts that overlap with Zoology. For example, the study of plant-animal interactions, such as pollination or seed dispersal, involves the understanding of both Botany and Zoology.

3. Career Opportunities:
- By choosing both Botany and Zoology as optional subjects, you can open up a wide range of career opportunities. You can pursue a career in research, teaching, environmental conservation, agriculture, forestry, or even work in museums or botanical gardens.

4. Comprehensive Preparation:
- Opting for both Botany and Zoology can also help you in your overall preparation for competitive exams like the UPSC. Many questions in the exams are based on the understanding of both plant and animal life, and having knowledge in both subjects can give you an edge.

5. Personal Interest:
- Ultimately, the choice of optional subjects should be based on your personal interest and aptitude. If you have a genuine interest in both Botany and Zoology and enjoy studying the intricacies of plant and animal life, then choosing both as optional subjects can be a rewarding experience.

In conclusion, you can definitely choose Botany as an optional subject along with Zoology. It will provide you with a broader understanding of the biological world, open up various career opportunities, and enhance your overall preparation for competitive exams. Make sure to consider your personal interest and aptitude before making a final decision.