Problem: a right triangle with sides 3 cm , 4 cm and 5 cm is rotated about the side of 3 cm to form a cone . the volume of the cone so formed is 
Options: ['a ) 12 π cm 3', 'b ) 15 π cm 3', 'c ) 16 π cm 3', 'd ) 20 π cm 3', 'e ) none']
a