Addition of phosphate fertilisers to water bodies causes

Which of the following is harmful to calcium-containing structures and is responsible for causing cough and throat irritation in humans?

How much carbon dioxide gas is removed from the atmosphere annually at the end of the process of photosynthesis?

The greenhouse gas(es) is/are:
$A$. Carbon dioxide
$B$. Oxygen
$C$. Water vapour
$D$. Methane
Choose the most appropriate answer from the options given below:

$A$ water sample has $ppm$ level concentration of following anions: $F^{-} = 10 \ ppm$,$SO_4^{2-} = 100 \ ppm$,$NO_3^{-} = 50 \ ppm$. The anion/anions that make the water sample unsuitable for drinking is/are:

Green plants use carbon dioxide during photosynthesis and release oxygen,yet carbon dioxide is considered responsible for the greenhouse effect. Why?