Q1. Which among the following is produced by a fungus?
A Citric acid Correct
B Butyric acid
C Acetic acid
D Lactic acid
Explanation
Citric acid is classically produced by the fungus Aspergillus niger in industrial fermentation, so it fits the question directly. Butyric acid is mainly linked with bacterial fermentation by Clostridium species, not fungal production. Acetic acid is produced by acetic acid bacteria during oxidation of ethanol. Lactic acid is formed chiefly by lactic acid bacteria such as Lactobacillus. The key idea is the organism used in standard commercial production: citric acid has a well-known fungal route, while the other acids are associated mainly with bacterial processes.