Grapes harvested and crushed into juice will often produce a fermented beverage containing alcohol. Grains (such as wheat, barley, rye, or corn) will also produce an alcoholic beverage if they are soaked and allowed to ferment. Which of the following organisms, naturally present in the environment, is the likely cause of the fermentation? a. angiosperms
b. yeasts
c. basidiomycetes
d. ciliates

b. yeasts

Explanation:

According to this question, certain crops and grains that contains sugar such as grapes, wheat, barley, rye etc. produce an alcoholic beverage via fermentation. This fermentation process is naturally carried out by YEAST cells.

Yeasts are fungi capable of undergoing both aerobic and anaerobic cellular respiration (fermentation) depending on the availability of oxygen. Fermentation carried out by yeasts breaks down sugar in substances to alcohol (ethanol). In other words, the sugar contents of those crops is being broken down into alcohol by fermentation process carried out by YEASTS.

b. the carbon cycle ensures living things have a source of hydrogen

i think the answer is b.