coal burning
B.
nuclear power
C.
solar heating
Solar heating is the system composed of a fluid system to move the heat from the collector to its point of usage and a reservoir to stock the heat
Explanation:
The options given here like coal burning uses solid material as the source to heat and to generate energy. Similarly, nuclear power also requires solid particles like atoms or neutrons to strike the moderators forming energy.
In both of these cases, fluid system is present but it is used completely as coolant and to maintain the temperature. Thus, the remaining system that is solar heating has been done for water tanks where the fluid as water is used to move the heat from its collector to its point of usage. Even in solar system it is used as reservoir to stock the heat.
Light from the stars is visible light and travels in longitudinal waves. Longitudinal waves require a medium to travel; therefore, light is reflected off particles of matter in space to be seen on the earth.
B.
Light from the stars is visible light and travels as surface to surface waves. Surface waves require a medium to travel; therefore, light travels from the surface of the star to the surface of the earth.
C.
Light from the stars is visible light and travels in electromagnetic waves. Electromagnetic waves require a medium to travel; therefore, light is reflected off particles of matter in space to be seen on the earth.
D.
Light from the stars is visible light and travels in electromagnetic waves. Electromagnetic waves do not require a medium to travel; therefore, light travels through the vacuum of space to be seen on the earth.
I think it is D
( Subject: Science )
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