Ans.
The endospores are dormant, non-reproductive, tough bacterial spores that ensure the survival of bacteria in adverse conditions. During environmental stress, such as starvation, desiccation (extreme dry), radiation, and chemical treatment, many bacteria form dormant endospores. These endospores germinate again when the conditions become favorable.
Therefore, if drought conditions lead the stream to dry up, the bacteria that live there, would produce endospores to survive.
Thus, the correct answer is 'option 4).'
