According to the study led by Mr. Newchurch, which of the following statements is TRUE

A．The ozone layer was increasing by 8 percent every 10 years since the late 1970s.
B．In the past few years, the decrease rate of the ozone has been steady.
C．The atmosphere is beginning to gain ozone now.
D．We'll have a full recovery of ozone in 50 years if the Montreal Protocol is well observed.