How does sound travle diffrently in different mediums

The difference in speed and the distance a sound wave travels in different mediums is directly dependent on what state the medium is in. as sound waves travel by the collision of particle to another they will travel faster and further in a solid as all the atoms are close together in liquid the speed will decrease as will the distance traveled and in gas the speed decreases even more because the molecules move further away from one another this is why sound cannot travel in a vacuum.  

The correct answer is b

I'm not sure but i will try to find out