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
${\rho _1} < {\rho _3} < {\rho _2}.$