Which of the following circumstances is responsible for generating particulate matter? airborne, odor-causing pathogens
gases escaping from manure piles
combustion of manure piles in hot weather
evaporation from contaminated groundwater

combustion of manure piles in hot weather

Explanation:

A manure piles are heap of animal waste or excreta mainly the waste from horse manure and the bedding which is stored to decompose and reduce in bulk.

Particulate matter is a mixture of small particles as well as liquid droplets that causes pollution and is harmful to health.

Burning of manure piles can cause to fly the dust and the dirt in the animal manure in the air and it leads to particulate matter suspended in the air.

the answer that best describes the relative refractory period in the neuron is the resting membrane potential is restored, but concentrations of sodium and potassium are not restored to their original state.

the refractory period is the time during which another stimulus given to the neuron will not lead to a second potential. thus, because na+ channels are inactivated during this time, additional depolarizing stimuli do not lead to new action potentials.  

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the correct option is option d