Of all psychoactive substances, has the longest history of widespread use.

Alcohol is the psychoactive substance that has the longest history of being used widespread. Around 7000 B.C., alcoholic drinks such as fermented beverage was already existing and was used in China. Before fermented drinks was produced by using the ingredients like honey and yeast. It is also noted that drinking wine is good for the heart. 

a. the production of carbon dioxide through the process of photosynthesis

this is math not biology xd