In DNA technology, the term 'vector' can refer to:

• A. The enzyme that cuts DNA into restriction fragments.
• B. The sticky end of a DNA fragment.
• C. A SNP marker.
• D. A vehicle used to transfer DNA into a living cell.

Answer: (D)

Verified step by step guidance

1. Understand the context: In DNA technology, a 'vector' is a tool used to introduce foreign genetic material into another cell.
2. Identify the role of a vector: It acts as a vehicle to transfer DNA, which can be a plasmid, virus, or other systems that can carry DNA into a host cell.
3. Differentiate from other terms: A restriction enzyme cuts DNA, sticky ends are the overhangs created by these cuts, and SNP markers are variations in a single nucleotide.
4. Recognize the application: Vectors are crucial in genetic engineering, gene therapy, and cloning as they facilitate the insertion of new genes into organisms.
5. Conclude with the correct definition: A vector is specifically used to transfer DNA into a living cell, enabling the study and manipulation of genes.