This is used in the preparation of alcohol

The correct option is Saccharomyces.

Saccharomyces, commonly known as yeast (specifically Saccharomyces cerevisiae or brewer's yeast), is a single-celled fungus widely used in the preparation of alcohol.
It plays a critical role in the biological process of fermentation.

During anaerobic respiration (fermentation), Saccharomyces converts sugars (like glucose, fructose, and sucrose found in fruit juices or grains) into ethanol (alcohol) and carbon dioxide.
The chemical equation representing this biochemical process is:
$C{H}_{12}{O}_6\to 2C_2{H}_{5}OH+2C{O}_2$

Here is a brief overview of why the other options are not used for preparing alcohol:
1. Acetobacter: This bacterium converts ethanol into acetic acid, which is used to make vinegar rather than alcohol.
2. Lactobacillus: This bacterium converts lactose into lactic acid, which is essential for curdling milk to make yogurt and cheese.
3. Penicillium: This is a fungus used to produce the antibiotic penicillin and in cheese ripening, but not for producing alcohol.