**Core Concept**
The creep in low copper amalgam refers to the gradual deformation or flow of the amalgam over time due to the plastic deformation of the gamma-2 (γ2) phase, which is a copper-tin alloy. This phenomenon is more pronounced in low copper amalgam restorations.

**Why the Correct Answer is Right**
The creep in low copper amalgam is primarily attributed to the plastic deformation of the γ2 phase, which is a copper-tin alloy. The γ2 phase has a higher tin content and a lower copper content compared to the γ1 phase, making it more prone to deformation under stress. The deformation of the γ2 phase leads to the creep of the amalgam, resulting in a gradual change in its shape and size.

**Why Each Wrong Option is Incorrect**
**Option A:** Incorrect because the creep in low copper amalgam is not primarily due to the corrosion of the amalgam.
**Option B:** Incorrect because the creep in low copper amalgam is not attributed to the formation of porosity within the amalgam.
**Option C:** Incorrect because the creep in low copper amalgam is not primarily due to the thermal expansion and contraction of the amalgam.

**Clinical Pearl / High-Yield Fact**
To minimize the creep in low copper amalgam restorations, dentists can use high copper amalgam or alternative restorative materials that are less prone to deformation. Additionally, proper placement and finishing techniques can help reduce the risk of creep.

**Correct Answer: C. Creep is primarily due to the plastic deformation of the γ2 phase.**