Answer: Dark matter may be<u> </u>Dark matter form <u>the cause of the expansion of the universe and a new form of subatomic particle.</u>
Explanation:
85% of the matter of the universe. scientists don't know exactly what makes up dark matter. It may be made of baryonic or non-baryonic particles or some new subatomic particles. No light emits from it thus it is named dark matter. Only its gravitational effect is observable which led to its discovery.The velocity of stars is different in different regions of galaxy. It is also thought to be cause of expansion of universe.
Thus, the correct answer is: Dark matter may be<u> the cause of the expansion of the universe and a new form of subatomic particle.</u>