An important requirement of fermentation is

Options

A. Oxygen
B. Zymase
C. Fe
D. `CO_(2)`

Answer

### Step-by-Step Solution:

1. **Understanding Fermentation**: Fermentation is a metabolic process that converts sugar to acids, gases, or alcohol in the absence of oxygen. This process is known as anaerobic respiration.

2. **Identifying the Requirements**: The key requirement for fermentation is the absence of oxygen. This distinguishes fermentation from aerobic respiration, which requires oxygen.

3. **Examining the Role of Enzymes**: During fermentation, specific enzymes are necessary to facilitate the breakdown of carbohydrates. In alcoholic fermentation, for example, the enzyme complex known as zymase plays a crucial role. Zymase is not a single enzyme but a group of enzymes that work together to convert pyruvate into ethyl alcohol.

4. **Types of Fermentation**: There are different types of fermentation, with alcoholic fermentation and lactic acid fermentation being the most common. Alcoholic fermentation occurs in yeast and certain bacteria, while lactic acid fermentation occurs in muscle cells and some bacteria.

5. **Conclusion**: The important requirement for fermentation is the presence of specific enzymes (like zymase) and the absence of oxygen. Therefore, the correct answer to the question is the presence of the enzyme complex zymase.