The ribose sugar is commonly found in ______ molecule.

Explanation

**Step-by-Step Solution:**

1. **Identify the Sugar**: The question asks about ribose sugar, which is a type of sugar that is important in biological molecules.

2. **Understand the Context**: Ribose sugar is a pentose sugar, meaning it has five carbon atoms. It is a key component of certain nucleic acids.

3. **Determine the Molecule**: Ribose sugar is primarily found in RNA (Ribonucleic Acid). RNA is one of the two main types of nucleic acids, the other being DNA.

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