For cylinders to be similar, the ratio between their height and radius must be equal.Our cylinder's ratio is :
[tex]\frac { length }{ radius } =\frac { 15 }{ 3 } \\ =5[/tex]
The only cylinder with same ratio is the one at the choice B.
[tex]\frac { length }{ radius } \frac { 25 }{ 5 } =5[/tex]