Official Solution:
This process resulted in a total of fifteen new townships; of which, to date, seven are still in existence.
A. of which, to date, seven are still in existence.
B. of which number, seven of the fifteen are still, to date, in existence.
C. of the number fifteen, seven, to date, are still in existence.
D. to date of these fifteen, seven are still in existence.
E. to date, seven of the fifteen are still in existence.
A. A semicolon separates two independent clauses. Thus the underlined part of the sentence must be an independent clause. However "of which...." is a dependent clause and hence wrong.
B. A semicolon separates two independent clauses. Thus the underlined part of the sentence must be an independent clause. However "of which...." is a dependent clause and hence wrong.
C. The usage of "number" is not correct: "fifteen" refers to the number of "townships", not the "number" itself. Hence usage of the word "number" is incorrect.
D. The phrase "of these fifteen" is misplaced. The placement here may indicate that the “date” belongs to “the fifteen”. Ideally the phrase “to date” should be separated by a comma so as to make it clear that the word “date” has no bearing to the prepositional phrase “of the fifteen”.
E. CORRECT. Two independent clauses are separated by the semicolon. The phrase “to date” is correctly set off by a comma, making the meaning clear.
Answer: E