The correct answer is (b) Saccharomyces cerevisiae.
Saccharomyces cerevisiae is a unicellular fungus that is widely used in the baking and brewing industries. It is also used in the production of ethanol, a biofuel that can be used as a substitute for gasoline.
Candida albicans is a yeast that is commonly found on the skin and mucous membranes of humans. It can cause infections, such as vaginal yeast infections and oral thrush.
Candida sloofi is a yeast that is found in soil and water. It is not known to cause any human infections.
Leucosporidium frigidum is a yeast that is found in cold environments, such as Antarctica. It is not known to cause any human infections.
Saccharomyces cerevisiae is the best choice for commercial production of ethanol because it is a fast-growing yeast that is able to ferment a variety of sugars. It is also a relatively inexpensive yeast to grow.