• Filter Frequency Response Characteristics:
• Band-pass filter passes signals within a designated continuous frequency band between a lower cutoff frequency ($f_1$) and an upper cutoff frequency ($f_2$), while heavily attenuating frequencies below $f_1$ and above $f_2$.
• Other Filters:
• Low-pass filter: Passes all frequencies from 0 to cutoff frequency $f_c$.
• High-pass filter: Passes frequencies above cutoff frequency $f_c$.
• Notch (Band-stop) filter: Rejects a narrow band while passing all others.
• Conclusion: Band pass filter (Option 3).

Correct option: (3) Band pass filter

• Types of Solar Stills in Solar Distillation:
• Standard passive and active solar distillation units include:
• Single-effect basin solar still: Simple airtight basin covered by inclined glass.
• Tilted-tray solar still: Multiple shallow stepped trays inclined toward the sun.
• Wick-type solar still: Utilizes capillary action through porous blackened fabric wicks.
• Multiple-effect solar stills are industrial active multi-stage distillation systems requiring external heat exchangers rather than standalone passive solar still classifications.
• Conclusion: Multiple effect solar still (Option 2).

Correct option: (2) Multiple effect solar still

• Tractor Operator Seat Ergonomics and Ride Vibration:
• Ride vibration in agricultural tractors consists of pitch, roll, and vertical bounce vibrations induced by terrain roughness.
• The Centre of Gravity (CG) of the tractor experiences the minimum angular rotational acceleration and pitch motions.
• Positioning the operator's seat as near to the centre of gravity as practical isolates the driver from severe pitching and rolling whiplash amplitudes.
• Conclusion: Near to the centre of gravity (Option 2).

Correct option: (2) Near to the centre of gravity

• Furrow Opener Geometrical Classifications:
• Furrow openers in seed drills are categorized by the angle made with the soil surface:
• Acute angle openers: Penetrate by suction/cutting (e.g., Hoe type, Shovel type).
• Right angle openers: Vertical penetration (e.g., Double disc type).
• Obtuse angle openers: The cutting edge slopes backward forming an obtuse angle with the direction of travel, sliding over crop residues and trash without clogging (e.g., Stub runner type, curved runner).
• Conclusion: Stub runner type (Option 3).

Correct option: (3) Stub runner type