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.
Im not sure but i think none of them are correct
C. Combine the sentences to condense the repetitive info. about inprovement.
Answer:
Because the more they accomplish a task the more their rank will increase
