Read the following text and answer the question on the basis of the same:
DNA, a long polymer of deoxyribonucleotide. These substances to be acidic hence the named nucleic acid. The basic unit of DNA is a nucleotide which has three components a nitrogenous base, a pentose sugar (deoxyribose) and a phosphate group. There are two types of nitrogenous bases in DNA, Purine and Pyrimidine. J. Watson and E. Crick proposed a double helix model for the structure of DNA. There are four types of DNA i.e., A, B, C, Z.
Which DNA form has maximum number of base pairs per turn?

Options

A. A-DNA
B. B-DNA
C. C-DNA
D. Z-DNA

Explanation

To answer the question about which DNA form has the maximum number of base pairs per turn, we can follow these steps:

### Step-by-Step Solution

1. **Understand the Structure of DNA**:
- DNA is composed of nucleotides, which include a nitrogenous base, a pentose sugar (deoxyribose), and a phosphate group.
- There are two types of nitrogenous bases: purines and pyrimidines.

2. **Identify the Types of DNA**:
- The text mentions four types of DNA: A, B, C, and Z.

3. **Review the Characteristics of Each DNA Type**:
- The A-DNA and B-DNA forms are the most common, with B-DNA being the most prevalent in biological systems.
- Z-DNA has a unique zigzag structure.

4. **Determine the Base Pairs per Turn**:
- According to the information provided, B-DNA typically has about 10 base pairs per turn.
- Z-DNA, due to its zigzag structure, has more base pairs per turn, specifically around 12 base pairs.

5. **Conclude the Answer**:
- Based on the comparison, Z-DNA has the maximum number of base pairs per turn, which is greater than that of A-DNA and B-DNA.

### Final Answer
The DNA form that has the maximum number of base pairs per turn is **Z-DNA**.