**Core Concept**
The question is based on the principles of **dental restorative procedures**, specifically the steps involved in preparing a tooth for a composite restoration. This includes **etching**, which is a crucial step for creating a strong bond between the tooth and the composite material.

**Why the Correct Answer is Right**
After etching, it is essential to wait for a specific time before rinsing to allow the **etchant** (usually phosphoric acid) to fully react with the tooth enamel and create microporosities. This time allows for optimal **micromechanical retention**. The recommended waiting time is typically around 20 seconds, but this can vary based on the specific etching protocol and material being used.

**Why Each Wrong Option is Incorrect**
**Option A:** Waiting for only 5 seconds would not be sufficient for the etchant to fully react with the enamel.
**Option B:** 10 seconds is still too short for optimal etching.
**Option D:** 60 seconds is excessively long and could lead to **over-etching**, potentially damaging the tooth structure.

**Clinical Pearl / High-Yield Fact**
Remember, the goal of etching is to create a strong, durable bond between the tooth and the composite material. Always follow the manufacturer's instructions for the specific etching product being used.

**Correct Answer:** C. 20 seconds