Soil is a mixture of
a. solids
b. solids, liquids, and gases
c. solids and liquids
d. solids and gases

b. solids, liquids, and gases

Explanation:

A soil is a mixture of solids, liquids and gases. The solids are in the form of coarse to fine sediments which are added up to the soil by the weathering of the parent rocks. The liquids are in the form of water which adds up in the soil through the tiny pores by sources like river, rainfall, oceans and others. The gases such as carbon dioxide, oxygen, nitrogen oxides diffuse into the soil through tiny pores these are essential for the growth of plants and soil microorganisms.  

significant amounts of nitrogen oxides, carbon monoxide, and other pollution

explanation:

passenger vehicles are a major pollution contributor, producing significant amounts of nitrogen oxides, carbon monoxide, and other pollution. in 2013, transportation contributed more than half of the carbon monoxide and nitrogen oxides, and almost a quarter of the hydrocarbons emitted into our air.