A stretch of DNA consisting of 10-20 bases is most appropriately be called as `:`

Options

A. Polynucleotide
B. Nucleotide
C. Nucleoside
D. Oligonucleotide.

Answer

To solve the question regarding what a stretch of DNA consisting of 10-20 bases is most appropriately called, follow these steps:

### Step 1: Understand the Definitions
- **Nucleotide**: The basic building block of DNA and RNA, consisting of a nitrogenous base, a sugar (deoxyribose in DNA), and a phosphate group.
- **Nucleoside**: A molecule consisting of a nitrogenous base and a sugar, but without the phosphate group.
- **Polynucleotide**: A long chain of nucleotides linked together, typically referring to the entire DNA or RNA molecule.
- **Oligonucleotide**: A short strand of nucleotides, typically consisting of 10 to 20 bases.

### Step 2: Analyze the Options
Given the definitions:
- Since the question specifies a stretch of DNA that is 10-20 bases long, it is too short to be classified as a polynucleotide.
- It cannot be referred to as a nucleotide because that term describes a single unit, not a stretch of bases.
- It is not a nucleoside since that lacks the phosphate group.
- Therefore, the most appropriate term for a stretch of DNA consisting of 10-20 bases is **oligonucleotide**.

### Step 3: Conclusion
The correct answer is **oligonucleotide**.

---