Correct Answer - C
After collision balls exchange their velocities
i.e., `v_A=sqrt(2gh) and v_B=sqrt(2g(4h))=2sqrt(2gh)`
Height attained by A will be `h_A=v_A^2/(2g)=h`
But path of B will be first straight line and then parabolic as shown in figure.
Using energy conservation for ball B.
`1/2mv_B^2=1/2mv^2+mgh " " or "" v=sqrt(6gh)`
`therefore h_B=h+(v^2sin^2 60^@)/(2g)=h+(9h)/4=(13h)/4`
Hence, `h_A/h_B=4/13`