Smog. Im pretty sure smog is the only unhealthful air pollution on this list.
Answer:
Sensory receptor interact with stimuli, such as light sound temperature and pain which is transformed into the code that is carried to the brain by the chain of neurons. Once the signal reaches he end of an axon, which is at the end of neuron, a neurotransmitter is released and the process repeats.
Answer would be D. The ecliptic would be path the Sun appears to move during the day.
D.The moon’s orbit must cross the plane of the ecliptic
It is the Watt per square meter, or W/m2.