a
From the figure it is clear that liquid \(1\) floats on liquid \(2\).

The lighter liquid floats over heavier liquid. Therefore 

we can conclude that \({\rho _1} < {\rho _2}\)

Also \({\rho _3} < {\rho _2}\) otherwise the ball would have sink to the bottom of the jar.

Also \({\rho _3} < {\rho _1}\) otherwise the ball would have floated in liquid \(1\). From the above discussion we conclude that

\({\rho _1} < {\rho _3} < {\rho _2}.\)