Answer:
A system that uses the sun's energy without requiring mechanical devices (pumps or fans) to distribute the collected heat are called solar system while radiator system uses fuel to heat the water. in active solar heating system, the SUN's energy used to heat water.
The difference between these two questions is that one has a scientific answer for that question. The one that says, " Can dogs identify colors?" is scientific because it can be answered scientifically but the one that says, "Are dogs better pets than cats?" cannot be answered scientifically.
~Hope that this makes since and helps
I think the answer would be A , break the darkness period with a flash of light for some time so that the plants can bloom all year round.