Answer:
Option C
Step-by-step explanation:
The habitat and fooding related habits of Bank swallows will change when their population is negatively impacted and they they prefer to discontinue their old habits.
earlier the bank swallows make nests on the banks of river even during the water rise in river, but since the population has reduced, this habit of bank swallows is also practiced by a lesser number of birds and hence only few bank swallows make nest during the time period of high water rise in river.
Thus, option C is correct