**Core Concept**
Free ribosomes are responsible for the synthesis of proteins that are not destined for cellular compartments or organelles. These proteins are typically involved in cellular processes such as metabolism, DNA replication, and protein folding.

**Why the Correct Answer is Right**
Ribosomes that are free-floating in the cytosol, not attached to the endoplasmic reticulum, are responsible for the synthesis of proteins that remain in the cytosol. These proteins often have roles in cytosolic metabolic pathways, regulation of gene expression, or as structural components of the cytoskeleton. The proteins synthesized by free ribosomes are not subject to the quality control mechanisms that occur in the endoplasmic reticulum and Golgi apparatus, which is why they do not require modification or transport to other cellular compartments.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not specify a protein that is synthesized in free ribosomes.
**Option B:** This option is incorrect because it is a protein that is typically synthesized in the mitochondria, which is a separate cellular compartment with its own ribosomes.
**Option C:** This option is incorrect because it is a protein that is synthesized in the endoplasmic reticulum, which is a membrane-bound organelle with its own ribosomes.

**Clinical Pearl / High-Yield Fact**
The proteins synthesized in free ribosomes are often involved in cellular processes that are critical for cellular homeostasis, such as protein degradation, DNA repair, and metabolic regulation.

**Correct Answer:** C.