**Core Concept**
Mitochondrial DNA (mtDNA) is a circular, double-stranded molecule found in the mitochondria, the powerhouses of eukaryotic cells. It encodes for 13 proteins essential for the electron transport chain, which generates the majority of ATP in the cell.

**Why the Correct Answer is Right**
Mitochondrial DNA is unique in that it is inherited solely from the mother, as only egg cells contribute mtDNA to the zygote. This is due to the fact that mitochondria are present in the egg cell but are not present in the sperm cell, except for a small number of mitochondria in the sperm tail. The mtDNA is then passed down through the maternal lineage, resulting in a phenomenon known as maternal inheritance.

**Why Each Wrong Option is Incorrect**
**Option A:** Mitochondrial DNA is a linear molecule. This is incorrect because mtDNA is actually a circular molecule.
**Option B:** Mitochondrial DNA encodes for all proteins in the mitochondria. This is incorrect because while mtDNA encodes for 13 proteins, many mitochondrial proteins are encoded by nuclear DNA and must be imported into the mitochondria.
**Option C:** Mitochondrial DNA is inherited from both parents equally. This is incorrect because, as mentioned earlier, mtDNA is inherited solely from the mother.

**Clinical Pearl / High-Yield Fact**
A key clinical correlation of mitochondrial DNA is the presence of mitochondrial myopathies, which are a group of disorders caused by mutations in mtDNA. These disorders can affect various systems, including the nervous system, muscles, and heart.

**Correct Answer:** C. Mitochondrial DNA is inherited from both parents equally.