Answer:
1. A. Volcanic eruptions
2.B. Greenhouse effect
Explanation:
1. Volcanic eruption produce greatest atmospheric particulates. Because when volcano erupt it ejects lava, rocks, dust and gases. These are called ejecta. In the given options in the question volcanic eruptions produce the most dust in atmosphere than plant respiration, hurricanes and erosion.
2. With a emission of carbon dioxide, methane and water vapor trapping heat in the earth atmosphere is called greenhouse effect.