Over the past 20 years, the major pollutants in our world have
a. decreased significantly
b. increased significantly
c. stayed at the same levels
d. decreased slightly

Over the past 20 years, the major pollutants in our world have increased significantly (b).

Further Explanation:

Pollutants are defined as the substance which causes pollution. Pollutants can be present in any forms from gaseous to solid. The pollutants can persist in the environment and keep on causing damage to the different ecological niche.

The example of pollutants can be,

Gaseous- Carbon dioxide, carbon monoxide, nitrogen oxide, CFCs, etc.

Liquid- Effluents from industries, agricultural runoff, etc.

Solid- Suspended particles, minute asbestos particles, etc.

Pollutants can be degradable or non-biodegradable depending upon its persistence in the environment. The pollutant which easily degrades by the action of the natural forces is termed as bio-degradable pollutant. The non-biodegradable pollutant tends to persist in the environment and keep on causing pollution.

Human activities have led to the increase in the amount of the pollutants in the environment from past many years.  This increase has been seen a peak in last few years as a result of industrialization and various other human activities.  

The increase in the pollutants has led to increase in the pollution. The pollution has hampered the living population that resides on the earth. If such a condition continues to increase the phenomenon such as global warming will be on the rise. This rise will cease the existence on the surface of the earth.

Learn More:

1.Learn more about catalyst

2.Learn more about influence of science on society

3. Learn more about carbon cycle

Answer Details:

Grade: High School

Subject: Biology

Chapter: Life and environment

Keywords:

Environment, organisms, pollution, pollutants, effluents, waste, industrial waste, industrial effluents, carbon dioxide, carbon monoxide, suspended particles, asbestos, global warming, cease in continuity of life, bio-degradable, non-biodegradable, ecology, ecological niche.

doctors i believe if i'm wrong sorry

the correct answer is 4) heat and pressure

metamorphic rocks arise from transformation of existing rocks types, in a process called metamorphism. during metamorphism the original rock(prolith) change into metamorphic rock by heating (150-200c) and pressure of more than 1000 bar. the original rock can be sedimentary, igneous, or existing metamorphic rock.