thE Author is trying to show in this ArtiClE thAt______.
A．usE oF suBstAnCEs mAy vAry From timE to timE
B．ABusE oF CErtAin suBstAnCEs is hArmFul For hEAlth
C．thE AttACk oF sEptEmBEr 11th hAs lEFt inCurABlE hArm to pEoplE's mEntAl hEAlth
D．tErrorist AttACk inCrEAsE AnxiEty AnD sEnsE oF insECurity Among rEsiDEnts