Answer
We can rank the liquids according to their weight per unit volume:
$c \gt b \gt a$
Work Step by Step
The apparent weight $W_{app} = weight-F_b$
where $F_b$ is the buoyant force, and $F_b = m_f~g$
where $m_f$ is the mass of the fluid that has been displaced.
For each depth $h$, the volume of fluid that has been displaced is equal in all three cases.
If $W_{app}$ is greater, then $F_b$ is smaller, then $m_f$ is smaller, then this liquid has a smaller density.
We can rank the liquids according to their weight per unit volume:
$c \gt b \gt a$
