Answer:
I have worked hard this week; now I understand how to use semicolons correctly.
(the one with the ';')
Step-by-step explanation:
A semicolon (;) creates a sense of pause for the reader. It creates a shorter pause than a period but a longer pause than a comma.
Using a semicolon in the sentence will keep it from being a run-off sentence or a incomplete sentence.
extra:
You know, even without knowing you can guess the answer because the sentence says "now I understand how to use semicolons".
Funny how the teacher did that question! =)