**Answer:**

During fermentation, one molecule of glucose is converted into either alcohol or lactic acid. This process occurs in the absence of oxygen and is called anaerobic respiration.

The overall process of fermentation starts with the glycolysis pathway, which occurs in the cytoplasm of the cell.

**Glycolysis:**
1. In the first step of glycolysis, glucose is converted into two molecules of pyruvate. This step requires the input of two ATP molecules.
2. In the second step of glycolysis, the two molecules of pyruvate are converted into two molecules of either alcohol or lactic acid, depending on the type of fermentation.
3. During this process, both alcohol fermentation and lactic acid fermentation produce two molecules of ATP through substrate-level phosphorylation.

**Alcohol Fermentation:**
1. In alcohol fermentation, the two molecules of pyruvate are converted into two molecules of acetaldehyde.
2. Acetaldehyde is then converted into two molecules of ethanol.
3. In this process, two molecules of NADH are also oxidized back to NAD+, allowing glycolysis to continue.
4. Two molecules of ATP are produced during the conversion of pyruvate to ethanol, resulting in a net gain of two ATP molecules.

**Lactic Acid Fermentation:**
1. In lactic acid fermentation, the two molecules of pyruvate are directly converted into two molecules of lactic acid.
2. In this process, two molecules of NADH are also oxidized back to NAD+, allowing glycolysis to continue.
3. Two molecules of ATP are produced during the conversion of pyruvate to lactic acid, resulting in a net gain of two ATP molecules.

Therefore, the net ATP synthesis after deducting the ATP utilized during glycolysis is two ATP molecules in both alcohol fermentation and lactic acid fermentation. Hence, the correct answer is option B) 4 ATP.