The answer is B about cycle
Positive - Due to urbanization, the people of rural areas settle in urban cites. These reduces the labour work which was done in rural areas and as they get water and electricity. The reduced labour work help them in maintaining their physical health
Negative - If people continues to enjoy the facilities and sit ideally doing nothing is much more worse than the above one. It causes obesity and can ultimately lead to heart attack
The difference in air pressure.