Question

How can plants help to decrease the amount of carbon dioxide in the atmosphere?

Answer 1

Plants consume the carbon that humans and other animals breath out as they produce oxygen that we breath in, so it is a sort of symbiotic relationship between humans and plants.

Answer 2

As plants and trees develop, they take carbon dioxide from the atmosphere and turn it into sugars through photosynthesis. Moreover, planting extra trees could remove more carbon from the atmosphere and store it for a long time.

or

Plants and trees absorb carbon dioxide from the atmosphere and convert it to sugars through photosynthesis as they grow. Furthermore, by planting more trees, more carbon will be extracted from the atmosphere and deposited for a long time.

(both are the same they are just worded differently, pick which one you like best)