Vapor dispersion: a. eliminates the risk of contamination to emergency responders and the environment.
b. is a more successful technique for controlling vapors than suppression.
c. reduces the concentration of the hazardous material in the air.
d. is not a viable option when vapor suppression is unsuccessful.

c. reduces the concentration of the hazardous material in the air.

Explanation:

Pollution can be defined as the physical degradation or contamination of the environment through an emission of harmful, poisonous and toxic chemical substances.

Particulate population is a form of pollution that is responsible for the degradation of the environment.

Particulate matter is also referred to as particle pollution or atmospheric aerosol particles and it can be defined as a complex microscopic mixture of liquid droplets and solid particles that are suspended in air. Other forms of particle pollution includes space debris and marine debris.

Some examples of particulate pollution are dusts, soot, dirt, smoke, etc.

Basically, various anthropogenic activities such as construction and agriculture are primary sources of particulate matter because they're capable of causing particle pollution on their own. The other sources of particle pollution is the secondary source which includes factories, cars, trucks, etc.

Vapor dispersion can be defined as a process which is typically used for removing particle pollutants from the atmosphere through the use of vapor or steam.

Hence, vapor dispersion when adopted, reduces the concentration of the hazardous material such as soot, dusts, smoke, etc., in the air.

i think it is true since you can test the answer and can use observations to complete it.