Theworld'ssuppliesofcopper（） A: havegraduallybeingexhausted B: aregraduallyexhausted C: hasbeengraduallyexhausted  D: arebeinggraduallyexhausted

Theworld’ssuppliesofcopper______. A: havebeengraduallybeingexhausted B: hasgraduallyexhausted C: aregraduallyexhausted D: arebeinggraduallyexhausted