Increasing carbon dioxide
concentration
increases the
rate of
photosynthesis
as carbon
dioxide (CO2) is
a
in
photosynthesis.
Above a certain
concentration,
further
increases in
concentration
do not increase
the rate of
photosynthesis
and it stops
being a limiting
factor.

Increasing  carbon dioxide  concentration  increases the  rate of  photosynthesis  as carbon  dioxide (CO2) is a limiting factor.

Explanation:

The photosynthetic rate is affected by certain factors, these can end up minimizing the potential amount of carbohydrate made by photosynthesis. For this type of biosynthesis, carbon dioxide is essential: it provides the inorganic carbon that is incorporated into carbohydrate molecules.

A decrease in the concentration of the available carbon dioxide may slow the photosynthetic rate.

sulfur dioxide

explanation: acid rain is caused by a chemical reaction that begins when compounds like sulfur dioxide and nitrogen oxides are released into the air. these substances can rise very high into the atmosphere, where they mix and react with water, oxygen, and other chemicals to form more acidic pollutants, known as acid rain.

b is the correct answer