【单选题】In the sentence 'an area covering 30% of the earth's land surface is desert, becoming desert, or in danger of becoming desert' , the part of ' is desert, becoming desert, or in danger of becoming dese...
A.
is becoming desert, has become desert, or will becoming into desert
B.
has been desert, is becoming desert, or will become into desert
C.
is becoming desert, will become desert, or becomes into desert
D.
has been desert, is becoming desert, or will become into desert