Select the correct answer from the following for DNA can be
1. A-DNA`" "`2. B-DNA
3. Z-DNA `" "` 4. Y-DNA.

Options

A. 1, 2 and 3 correct
B. 1 and 2 are correct
C. 2 and 4 correct
D. 1 and 3 correct.

Answer

To solve the question, we need to identify the correct types of DNA from the given options. Let's break it down step by step:

### Step 1: Understand the Types of DNA
DNA can exist in different structural forms, commonly referred to as A-DNA, B-DNA, and Z-DNA. Each of these forms has distinct structural characteristics.

### Step 2: Identify the Options
The options given are:
1. A-DNA
2. B-DNA
3. Z-DNA
4. Y-DNA

### Step 3: Analyze Each Option
- **A-DNA**: This is a right-handed double helix and is one of the known forms of DNA.
- **B-DNA**: This is the most common form of DNA and was described by Watson and Crick. It is also a right-handed double helix.
- **Z-DNA**: This is a left-handed double helix and is another recognized form of DNA.
- **Y-DNA**: This is not a recognized form of DNA in the context of molecular biology.

### Step 4: Conclusion
From the analysis, we see that A-DNA, B-DNA, and Z-DNA are all valid forms of DNA, while Y-DNA is not. Therefore, the correct answer to the question is **B-DNA** (Option 2).

### Final Answer
The correct answer is **2. B-DNA**.

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