• Function of Bilge Keels on Fishing Vessels:
• Bilge Keels: Longitudinal hydrodynamic fins or structural plates welded along the turn of the bilge (chine) on either side of the vessel's hull near the midship section.
• When the vessel rolls transversely in sea waves, the bilge keels displace water, generating strong hydrodynamic eddies and viscous drag forces perpendicular to the rolling direction.
• This substantially damps and reduces the rolling motion of the vessel, improving navigational stability, sea-keeping ability, and crew safety without obstructing forward movement.
• Correct Option: Option 3 (reduces rolling of the boat).

• Computation of Irregular Land & Pond Areas:
• In surveying and civil layout of aquaculture ponds, areas bounded by irregular curves or irregular polygonal perimeters are evaluated using numerical integration formulas.
• Trapezoidal Rule: Assumes the irregular boundary between consecutive measured offsets consists of a series of straight trapezoidal chords:

where $d$ is the common interval between perpendicular offsets ($y_i$).

• Correct Option: Option 2 (Trapezoidal rule).