"A branch of science concerned with the interrelationship of organisms and their environments" is called-

• "A branch of science concerned with the interrelationship of organisms and their environments" is called 'Ecology'.

• Ecology (noun)
- English Meaning: A branch of science concerned with the interrelationship of organisms and their environments.
- Bangla Meaning: বাস্তব্যবিদ্যা; যে বিদ্যায় পরিবেশের সঙ্গে জীবজগতের সম্পর্ক আলোচিত হয়।

• Other options:
- Cosmology (মহাবিশ্ব সম্পর্কিত বিজ্ঞান): A branch of metaphysics that deals with the nature of the universe.

- Meteorology (আবহাওয়াবিজ্ঞান): A science that deals with the atmosphere and its phenomena and especially with weather and weather forecasting.

- Archaeology (প্রত্নতত্ত্ব; প্রত্নবিদ্যা): The scientific study of material remains (such as tools, pottery, jewelry, stone walls, and monuments) of past human life and activities.

Source:
1. Oxford Dictionary.
2. Merriam-Webster Dictionary.