Explanation:
Germany's condition of reduction of population is because of pandemic effect on global recolation.
Positive:There would not be much pandemics, diseases,& so on.
Negative: There would be an effect on economy, there'll be few or less workers,so on.(This would be a larger effect than the positives of course)
One reason of undergrowth is of jobless rate & bare utilisation anticipation.

I think this is the answer.
Flood waters can be channeled to provide irrigation is true about the development of farming in Summer. The correct option among all the options that are given in the question is the last option or option "D". Without adequate amount of water, it is not possible to farm in the summer months.