Which of the following ions are furnished by acids in aqueous solutions?
A. [OH⁻] ions
B. [H⁺] ions
C. [H₃O⁺] ions
D. None of These

To determine which ions are furnished by acids in aqueous solutions, we need to understand the behavior of acids in water.

**Acids in Aqueous Solutions:**

When an acid dissolves in water, it donates protons (\( \text{H}^+ \) ions) to the water molecules. This results in the formation of hydronium ions (\( \text{H}_3\text{O}^+ \)) in the solution. Here's the detailed process:

1. **Dissociation of Acid:**
When an acid \( \text{HA} \) (where \( \text{A} \) is the anion) dissolves in water, it dissociates according to the following reaction:
\[ \text{HA} \rightarrow \text{H}^+ + \text{A}^- \]

2. **Formation of Hydronium Ion:**
The free protons (\( \text{H}^+ \)) released by the acid then interact with water molecules. This leads to the formation of hydronium ions:
\[ \text{H}^+ + \text{H}_2\text{O} \rightarrow \text{H}_3\text{O}^+ \]

Thus, in aqueous solutions, the \( \text{H}^+ \) ions are immediately hydrated to form \( \text{H}_3\text{O}^+ \) ions.

**Conclusion:**

- **Option A: \( \text{OH}^- \) ions** - These are hydroxide ions, typically found in basic solutions, not acidic solutions.
- **Option B: \( \text{H}^+ \) ions** - While acids release \( \text{H}^+ \) ions, they are quickly hydrated to form \( \text{H}_3\text{O}^+ \) ions.
- **Option C: \( \text{H}_3\text{O}^+ \) ions** - These are the actual ions present in aqueous solutions of acids, resulting from the hydration of \( \text{H}^+ \) ions.
- **Option D: None of These** - This is incorrect because \( \text{H}_3\text{O}^+ \) ions are indeed present in the solution.

Therefore, the correct answer is **C. \( \text{H}_3\text{O}^+ \) ions**.