Which of the following statements regarding ozone is incorrect ?

Options

A. Good ozone' is formed in the lower atmosphere (troposphere) that absorbs harmful UV rays coming from Sun, 'bad ozone' is present in the upper part of atmosphere (stratosphere) that harms plants and animals.
B. The thickness of the ozone in a column of air from the ground to the top of the atmosphere is measured in terms of Dobson units (DU).
C. Recognising the deleterious effects of ozone depletion, an international treaty, known as the Montreal Protocol, was signed at Montreal (Canada) in 1987 (became effective in 1989) to control the emission of ozone depleting substances.
D. None of these

Answer

A