The answer to this question is B. Cold Front
Hydrosphere and atmosphere. those are the only 2 spheres that interact with each other in the air.
I would say that housing availability, inadequate services, pollution and migration from rural areas all present challenges to the regional urban areas but not reduced population. If there is migration to the cities then these above three problems must be dealt with to accommodate the new citizens.
Answer:
special relativity and general relativity. Special relativity applies to all physical phenomena in the absence of gravity. General relativity explains the law of gravitation and its relation to other forces of nature.
Explanation: