**Core Concept**
Hexokinase is a key enzyme in glucose metabolism, responsible for phosphorylating glucose to form glucose-6-phosphate. This step commits glucose to the glycolytic pathway, initiating cellular metabolism. Hexokinase is a cytoplasmic enzyme, whereas many other metabolic enzymes are located within specific organelles.

**Why the Correct Answer is Right**
Hexokinase is indeed a cytoplasmic enzyme, meaning it is active within the cell's cytosol. The correct location of hexokinase within the cell is crucial for its function in glycolysis. In contrast, the other enzymes listed are primarily found in different cellular compartments.

**Why Each Wrong Option is Incorrect**
* **Option A:** Trypsin is a proteolytic enzyme found in the pancreas and small intestine, where it breaks down proteins. It is secreted into the digestive tract, where it is active in the extracellular space, not within the cell.
* **Option B:** Futnerase is not a commonly recognized enzyme in medical literature. However, it is possible that this option is a distractor or a typographical error. Assuming it is meant to be "futile" or "futile cycle" enzyme, it could refer to an enzyme involved in futile cycles within cells, but the term is not standard.
* **Option D:** Alcohol dehydrogenase is an enzyme that catalyzes the conversion of alcohol to acetaldehyde and is found in various tissues, including the liver. It is active within the cell, particularly in the cytosol.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that cellular localization and enzyme activity are critical for understanding metabolic pathways. This question highlights the importance of cellular compartmentalization in enzymatic function.

**✓ Correct Answer: C. Hexokinase**