Answer:
D. improve fertility
Step-by-step explanation:
A garden supply company has an advertisement selling beneficial bacteria. They claim that the bacteria will help gardeners grow better gardens because of better soil.
This claim is simply based on the premise or fact that some bacterias can improve fertility of the soil.
Some species of bacterias are living microorganisms that are capable of decomposing organic matter into nitrogen, carbon and other nutrients, which are then released into the soil in a plant available form when in excess and this cycle continues with reproduction of new bacterias.
Some examples of these bacterias are Klebsiella, Anabaenopsis, Beijerinckia, Azotobacter, Clostridium, Anabaena, Nostoc, Bacillus etc.