Step 1: Understand the history of biology.
- The word 'biology' was coined by Jean-Baptiste Lamarck and got popularized by Charles Darwin as the study of life.
Step 2: Review the options.
- Aristotle is known for his work in biology but did not coin the term 'biology.'
- Gregor Mendel is known for his work in genetics, not the coinage of biology.
- Charles Darwin is often credited with popularizing the term 'biology,' though Lamarck is the one who first used it formally.
- Boveri made important contributions to cell biology but did not coin the term 'biology.'
Step 3: Conclude.
Charles Darwin is the most widely recognized figure associated with the popularization of the term 'biology,' making option (C) the correct answer.
Final Answer:
\[
\boxed{\text{Charles Darwin}}
\]