Anaerobic respiration in yeast produces carbon dioxide (CO2) and ethanol (C2H5OH) as end products. This process is also known as fermentation.

1. Anaerobic Respiration in Yeast:
Yeast is a single-celled organism that can undergo both aerobic and anaerobic respiration. In the absence of oxygen, yeast cells switch to anaerobic respiration to generate energy.

2. Glycolysis:
The first step in anaerobic respiration is glycolysis, which occurs in the cytoplasm of yeast cells. During glycolysis, glucose (C6H12O6) is broken down into two molecules of pyruvate (C3H4O3). This process involves a series of enzymatic reactions and produces a small amount of ATP (adenosine triphosphate).

3. Fermentation:
After glycolysis, yeast cells undergo fermentation to regenerate NAD+ (nicotinamide adenine dinucleotide), which is required for glycolysis to continue. There are two types of fermentation that yeast can undergo:

a. Alcoholic Fermentation:
In alcoholic fermentation, pyruvate is converted into ethanol (C2H5OH) and carbon dioxide (CO2). This process occurs in the absence of oxygen and is carried out by enzymes called alcohol dehydrogenase and pyruvate decarboxylase. The release of carbon dioxide is responsible for the formation of bubbles in dough during bread-making or the fizz in carbonated beverages.

b. Lactic Acid Fermentation:
In lactic acid fermentation, pyruvate is converted into lactic acid. This process is not commonly observed in yeast, but it occurs in some bacteria and human muscle cells during intense exercise when oxygen is limited.

4. End Products:
The end products of anaerobic respiration in yeast are carbon dioxide (CO2) and ethanol (C2H5OH). These molecules are released into the surrounding environment. The release of carbon dioxide creates bubbles, and the accumulation of ethanol contributes to the characteristic flavor and alcohol content of fermented products, such as beer, wine, and bread.

Therefore, option C, which includes CO2, C2H5OH, and energy, is the correct answer.