Chemicals are used for the treatment of diseases in prehistoric as well as in modern times. This branch of science is called.

Options

A. Physiotherapy
B. Chemotherapy
C. Homeopathy
D. Radiotherapy

Answer

To answer the question regarding the branch of science that deals with the use of chemicals for the treatment of diseases, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding the Context**: The question refers to the use of chemicals in treating diseases throughout history, which includes both prehistoric and modern practices.

2. **Identifying the Relevant Branch of Science**: The field that focuses on the study of drugs and their effects on the human body, particularly in treating diseases, is known as pharmacology.

3. **Defining Pharmacology**: Pharmacology is the branch of medicine and biology concerned with the study of drug action. It encompasses the understanding of how drugs interact with biological systems, their therapeutic effects, and their potential side effects.

4. **Narrowing Down to Specific Treatments**: While pharmacology is the broader field, the term "chemotherapy" is often specifically associated with the treatment of cancer using chemical substances. However, it is important to note that chemotherapy is a subset of pharmacology focused on cancer treatment.

5. **Final Answer**: Therefore, the correct answer to the question is that the branch of science dealing with the treatment of diseases using chemicals is called **Pharmacology**.