According to the Economist GMAT Tutor, the answer choice corresponding to the problem below is C, but how can the word "still" be a conjunction? Am I missing something or the answer explanation from Economist GMAT tutor is incorrect?
Here is the question
Even though the law mandates that all passengers in a vehicle wear a seat belt, still approximately 20% of the population refrain from doing so.
A. Even though the law mandates that all passengers in a vehicle wear a seat belt, still approximately
B. Even though the law mandates that every passenger in a vehicle wears a seat belt, approximately
C. The law mandates that all passengers in a vehicle wear a seat belt, still approximately
D. The law mandates that all passengers in a vehicle will wear a seat belt, yet around
E. Even though the law mandates that every passenger in a vehicle is wearing a seat belt, approximately