Answer:
b. an increase in the overall temperature of the Earth
Explanation:
In the recent years there has been an increase in the overall temperatures of the earth.
This is referred to as global warming that is caused by the greenhouse effect.
Global warming has come as a result of hazardous industrial development.
Industries emit harmful gases that form a cover layer to the sun thereby preventing penetrated light from escaping the earth while allowing heat to enter the earth.
