A DNA molecule is shaped like a:

• A. linear strand
• B. triple helix
• C. beta sheet
• D. double helix

Answer: (D)

Verified step by step guidance

1. Recall the fundamental structure of DNA as discovered by Watson and Crick, which is known as the double helix.
2. Understand that DNA consists of two strands twisted around each other, forming a helical shape, which is why it is called a double helix.
3. Recognize that a linear strand refers to a single, uncoiled strand, which does not accurately describe DNA's structure.
4. Note that a triple helix is a rare and unusual structure not typical of standard DNA molecules.
5. Remember that beta sheets are a type of protein secondary structure, not related to DNA.