Answer:
d. An essential nutrient may be depleted
Explanation:
A bacterial culture is characterized by 4 phases:
(1) Lag phase
(2) Log phase
(3) Stationary phase
(4) Decline phase
The stationary phase in bacterial culture is known as idiophase. By this phase, essential nutrients get depleted because a lot of bacterial cells are produced by cell division in the log phase which is a stage prior to stationary phase/idiophase. Due to the increase in number of bacteria, the biomass of the culture increases which results in the deprivation of nutrients.
Due to this deprivation, the bacterial cells start to undergo stress which further leads to the production of secondary metabolites which are toxic in nature. These secondary metabolites are also known as idiolites.
The reason why option (c) can't be included in the answer is because although secondary metabolites are produced in the stationary phase yet they are not the reason behind initiation of this phase, they are the impacts of this phase.
