The most abundant prokaryotes helpful to humans in making curd from milk and in production of antibiotics are the ones categorised as

Options

A. cyanobacteria
B. archaebacteria
C. chemosynthetic autotrophs
D. heterotrophic bacteria

Answer

D

Explanation

Heterotrophic bacteria are most abundant in nature. Many of them have a significant impact on human affairs. These are helpful in making curd from milk (e.g. Streptomyces sp.) and fixing nitrogen in legume roots (e.g. Rhizobium sp).