Answer:
Only the second and third statements are correct:
Doubling <em>r</em> quadruples the volume. 
Doubling <em>h</em> doubles the volume. 
Step-by-step explanation:
The volume of a cylinder is given by: 

We can go through each statement and examine its validity. 
Statement 1)
If the radius is doubled, our new radius is now 2<em>r</em>. Hence, our volume is: 

So, compared to the old volume, the new volume is quadrupled the original volume. 
Statement 1 is not correct. 
Statement 2)
Using the previous reasonsing, Statement 2 is correct. 
Statement 3)
If the height is doubled, our new height is now 2<em>h</em>. Hence, our volume is: 

So, compared to the old volume, the new volume has been doubled. 
Statement 3 is correct. 
Statement 4)
Statement 4 is not correct using the previous reasonsing. 
Statement 5)
Doubling the radius results in 2<em>r</em> and doubling the height results in 2<em>h</em>. Hence, the new volume is: 

So, compared to the old volume, the new volume is increased by eight-fold. 
Statement 5 is not correct.