• Search and Rescue Transponder (SART) Specifications:
• Search and Rescue Transponder (SART) is an essential maritime survival craft distress equipment mandated under the Global Maritime Distress and Safety System (GMDSS) IMO/SOLAS conventions.
• Operating Frequency: SART operates in the $9\text{ GHz}$ marine X-band radar frequency band ($9.2 - 9.5\text{ GHz}$).
• When interrogated by navigational radar pulses from search aircraft or vessels, it transmits a coded response that appears as a radial line of 12 distinct blips extending outwards from the survival craft on the radar screen.
• Correct Option: Option 3 (9GHz frequency band (9.2 to 9.5 GHz)).

• Propulsion of Deep-Sea Fishing Vessels:
• Deep-sea mechanized fishing vessels (such as trawlers, tuna longliners, and purse seiners) operate exclusively on marine diesel engines utilizing diesel fuel (High Speed Diesel, HSD / Marine Gas Oil, MGO).
• Reasons for Diesel:
• High fuel economy and thermal efficiency.
• Superior high-torque output required for dragging heavy trawl gears.
• Safety: Diesel has a high flash point ($\gt 60^\circ\text{C}$), preventing explosive fire hazards at sea, unlike low-flashpoint petrol (gasoline).
• Correct Option: Option 2 (Diesel).

• Marine Gearbox in Fishing Vessels:
• In a fishing vessel propulsion train, the marine reduction-reverse gearbox is installed between the main diesel engine and the propeller shaft.
• Primary Purpose:

• Directional Control: Engages multi-plate clutches to allow forward, reverse, and neutral propeller shaft rotation while the engine runs continuously in one direction.
• Speed Reduction: Steps down high engine crankshaft RPM ($1500-2000\text{ rpm}$) to efficient low propeller speeds ($300-500\text{ rpm}$).
  • Correct Option: Option 3 (Keeping the forward, reverse and neutral positions).

• 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).