**Core Concept**
Copper alloys, commonly used in dental restorations, are composed of various metals with copper as a primary component. The percentage of copper in these alloys determines their mechanical properties and corrosion resistance.

**Why the Correct Answer is Right**
High copper alloys, also known as copper-rich alloys, are used in dental restorations due to their favorable mechanical properties and biocompatibility. These alloys typically contain a high percentage of copper (13-30%), which enhances their corrosion resistance and strength. The addition of other metals, such as silver, tin, and zinc, helps to improve the alloy's mechanical properties and resistance to corrosion.

**Why Each Wrong Option is Incorrect**
**Option A:** 10-12% is too low for a high copper alloy, as it would not provide sufficient corrosion resistance and mechanical strength.
**Option B:** 0-6% is too low, as it would result in an alloy that is more susceptible to corrosion and lacks the desired mechanical properties.
**Option D:** 20-30% is partially correct but does not encompass the full range of high copper alloys, which can contain up to 30% copper.

**Clinical Pearl / High-Yield Fact**
When selecting a dental material, it's essential to understand the composition of the alloy and its properties. High copper alloys are often used in dental restorations due to their favorable mechanical properties and biocompatibility.

**✓ Correct Answer: C. 13-30%**