Answer:
(D) as charge
Step-by-step explanation:
Given statement is -
More than three times as many independent institutions of higher education charge tuition and fees of under $8,000 a year than those that charge over $16,000.
(A) than those that charge
(B) than are charging
(C) than to charge
(D) as charge
(E) as those charging
Answer is option D: "three times as many institutions charge tuition and fees of under $8,000 a year as charge over $16,000."
This option has the correct verb form and it does not include any non-parallel words.