The helical structure of DNA was discovered by :

Options

A. Sanger
B. Bloor
C. L. Pauling
D. Watson and Crick

Explanation

**Step-by-Step Solution:**

1. **Understanding the Question**: The question asks about the discovery of the helical structure of DNA. It is important to identify which scientists were responsible for this discovery.

2. **Identifying DNA Structure**: DNA is known to be the genetic material in living organisms and is characterized by its double helix structure. This structure is crucial for its function in storing and transmitting genetic information.

3. **Key Scientists**: The scientists who proposed the double helix model of DNA are James Watson and Francis Crick. They are credited with the discovery of the helical structure of DNA.

4. **Method of Discovery**: Watson and Crick utilized X-ray diffraction techniques to study the structure of DNA. This method allowed them to visualize the arrangement of atoms within the DNA molecule, leading to the conclusion that it has a double helical structure.

5. **Components of DNA**: DNA is made up of nucleotides, which consist of a nitrogenous base, a sugar group, and a phosphate group. These nucleotides form two strands that are held together by hydrogen bonds.

6. **Conclusion**: Based on the contributions of Watson and Crick, the correct answer to the question is that the helical structure of DNA was discovered by **Watson and Crick**.

**Final Answer**: The helical structure of DNA was discovered by **Watson and Crick**.

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