The pressure $P_1$ at a certain depth in river water and $P_2$ at the same depth in sea water are related as

The pressure $P_1$ at a certain depth in river water and $P_2$ at the same depth in sea water are related as :
(a) $P_1>P_2$ (b) $P_1=P_2$
(c) $P_1<P_2$ (d) $P_1-P_2$ = atmospheric pressure

The pressure P1 at the top a dam and P2 at a depth h from the top inside water are related as:

Pressure at free surface of a water lake is $P_1$, while at a point at depth $h$ below its free surface is $P_2$.
(a) How are $P_1$ and $P_2$ related ?
(b) Which is more $P_1$ or $P_2$ ?