A stream of waters holds thriving bacteria. If drought conditions caused the stream to dry up, how would the bacteria most likely respond to survive?

No because the bacteria thrives of of its natural environment

Certain bacteria can produce something called an endospore, which is a spore that contains DNA, cytoplasm, and a tough outer coating. They are only produced under times of stress when conditions are much less than ideal (ex. extreme heat/cold, drought, extreme radiation, lack of nutrients). Once conditions return to normal, the endospore returns to its bacterial form. Perhaps this is the answer?