Both DNA and RNA are polymers of basic repeating unit, called a ...........

Explanation

**Step-by-Step Solution:**

1. **Identify the Basic Repeating Unit**:
Both DNA (Deoxyribonucleic acid) and RNA (Ribonucleic acid) are types of nucleic acids. The basic repeating unit that makes up these nucleic acids is known as a nucleotide.

2. **Understand the Composition of a Nucleotide**:
A nucleotide consists of three components:
- A five-carbon sugar (pentose sugar)
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