The correct option is A 20 m/s
Pressure at hole, P2=3 atm
Pressure at open end of tank is P1=1 atm
Since the hole is also open to atmosphere, excess pressure P2−P1=2 atm at the hole is due to hydrostatic pressure of water column above the hole.
⇒ρgh=P2−P1=2 atm
Or, ρgh=2×105 N/m2
∴h=2×105103×10=20 m
Cross-sectional area of tank is very large compared to area of the hole (very small), i.e A1>>A2
Hence, we can apply formula for velocity of efflux at the bottom of the tank:
⇒v=√2gh
Or, v=√2×10×20
∴v=20 m/s