It could either be choice 3 or 4.
There is a topic: "Reasons why people should buy hybrid autos."
Misspelled words? Nope. Use spellcheck if not sure.
No errors. None to me (I don't know about structure errors)
Only two details... looks fishy...
Choose from the two.
Answer:
<em>"</em><em>She is enrolling in swim class because of this.</em><em>"</em><em> </em> uses progressive tense verb.
