For tEn yEArs thE proBlEm ABout thE wAtEr hAs not BEEn solvED, wE CAmE to think thAt it hAs BEEn A ______ proBlEm in this ArE
A、
A、pErpEtuAlB、pErsuAsivE
C、piCturEsquE
D、possEssivE