Dengue fever is caused by the dengue virus, which is transmitted primarily by the Aedes aegypti mosquito. This mosquito is active during the daytime and breeds in stagnant water. Aedes aegypti is known for its distinctive black and white markings and is commonly found in tropical and subtropical regions. It spreads dengue, chikungunya, and Zika virus. Anopheles mosquitoes transmit malaria, while Culex species transmit diseases like filariasis and West Nile virus. Thus, Aedes aegypti is the correct answer. Preventing mosquito breeding and avoiding bites are key measures to control dengue انتشار.

Kirthar range spans Sindh and Balochistan, so both A & B correct.

Platelets, also known as thrombocytes, are responsible for blood clotting. They are small cell fragments in the blood that play a crucial role in preventing excessive bleeding when a blood vessel is injured. When damage occurs, platelets gather at the site and form a plug. They also release chemicals that trigger a cascade of reactions, leading to the formation of fibrin, a protein that stabilizes the clot. Lymphocytes and monocytes are types of white blood cells involved in immunity, while red blood cells transport oxygen. Thus, platelets are the correct answer. Understanding blood components is essential for studying human biology and medical conditions like hemophilia.

Plants absorb nitrogen in usable forms like ammonia (NH3) or nitrates. Atmospheric nitrogen cannot be directly used without fixation.

Benjamin Franklin, a prominent American scientist and statesman, invented both the lightning rod and bifocal spectacles. His lightning rod invention emerged from his experiments with electricity, including the famous kite experiment, which demonstrated that lightning is a form of electrical discharge. The lightning rod protects buildings by directing electrical energy safely into the ground, preventing fires and structural damage. This invention had immediate practical importance and is still widely used today. Franklin also invented bifocal spectacles to address his own vision problems. These glasses combine two lenses in one frame, allowing a person to see both near and distant objects clearly without switching glasses. This was a major convenience and innovation in optics. Other options are notable scientists but unrelated to both inventions: Thomas Edison developed electric devices, Alessandro Volta invented the battery, and Benjamin Banneker was a mathematician and astronomer. Therefore, Benjamin Franklin is the correct answer, as he contributed significantly to both electrical science and practical inventions improving daily life.