The correct answer is option - D. the living world.
Explanation:
Biologists are the scientists that study of biology which is the study of the living world. Biology is the scientific study of life it also means bio means life and logy means study.
Biologists explore and research about the mechanism and questions about the living organisms. It is simply termed as science or study of living beings but it includes almost all and everything about the living world.
Thus, the correct answers is option D. the living world.
