not just ...but also 也对么？

mereimoun

OG12 第83题：
In 2000, a mere two dozen products accounted for half the increase in spending on prescription drugs, a phenomenon that is explained not just because of more expensive drugs but by the fact that doctors are writing many more prescriptions for higher-cost drugs.

A.    a phenomenon that is explained not just because of more expensive drugs but by the fact that doctors are writing
B.a phenomenon that is explained not just by the fact that drugs arebecoming more expensive but also by the fact that doctors are writing
C.    a phenomenon occurring not just because of drugs that are becoming more expensive but because of doctors having also written
D.    which occurred not just because drugs are becoming more expensive but doctors are also writing
E.    which occurred not just because of more expensive drugs but because doctors have also written

mereimoun

是5个都是not just，但不是每个都是 but also
我觉得 not just ...but...可能是not...but...的用法，所以才问啊。