Sentence Correction

A recent national study of the public schools shows that there are now one microcomputer for every thirty-two pupils, four times as many than there were four years ago

(A) there are now one microcomputer for every thirty-two pupils, four times as many than there were
(B) there is now one microcomputer for every thirty-two pupils, four times as many than there were
(C) there is now one microcomputer for every thirty-two pupils, four times as many as there were
(D) every thirty-two pupils now have one microcomputer, four times as many than there were
(E) every thirty-two pupils now has one microcomputer, four times as many as


I am confused between C and E . Please explain how the meaning has changed?

(C) ...., four times as many as there were 4 years ago.
This means that we are comparing a new ratio with a ratio that existed 4 years ago. New ratio vs old ratio - this is parallel comparison

(E) ...., four times as many as 4 years ago.
This means that we are comparing a new ratio with 4 years ago. Ratio vs 4 years ago are not parallel.