The correct option is (c).
Explanation
The Troposphere is the lowermost layer of the Earth's atmosphere, containing the bulk of the atmospheric mass and acting as the primary site for meteorological activities.
- Statement 1 is correct: The Troposphere is the lowest layer of the atmosphere, in direct contact with the Earth's surface. It is the most important layer for all biological activity.
- Statement 2 is incorrect: The average height of the troposphere is approximately 13 km, not 50 km. Its height varies by latitude, extending to roughly 8 km near the poles and up to 18 km at the equator due to strong convection currents. The altitude of 50 km corresponds to the upper limit of the Stratosphere.
- Statement 3 is correct: This layer contains the vast majority of the atmosphere's water vapour and dust particles. Consequently, almost all weather phenomena, including cloud formation, rainfall, fog, and storms, occur exclusively within this layer.
Key Takeaway: The Troposphere is characterized by a decrease in temperature with increasing altitude (normal lapse rate) and significant variation in thickness between the equator and the poles.