The Greek system of classifying climate is based on

Analyze the question: It asks what the ancient Greek system of classifying climate was based on. This is not the modern Köppen system, which uses rainfall, temperature and vegetation.

Explain the concept: The ancient Greeks (for example Parmenides and Aristotle) divided the world into climatic zones by latitude. They used the angle of the sun's rays, which determines how hot or cold a place is. Their three main zones were:

1. Torrid Zone (Tropics): very hot, between the Tropic of Cancer and the Tropic of Capricorn.
2. Temperate Zones: moderate temperatures, between the tropics and the polar circles.
3. Frigid Zone (Polar): very cold, beyond the Arctic and Antarctic Circles.

The names themselves (torrid, temperate, frigid) describe temperature only. The Greeks did not use rainfall, humidity or vegetation as the basis for these zones.

Step-by-step solution:

• Option B (rainfall and temperature): this is closer to Köppen's work, not the Greek system.
• Option C (rainfall and vegetation): this also reflects Köppen, who used vegetation as an indicator of climate.
• Option D (humidity): the Greeks did not use this.
• Option A (temperature): this matches the Greek zones of hot, temperate and cold.

Answer: A. temperature.

Exam tip: Link the Greeks with temperature zones (Torrid, Temperate, Frigid). Link Köppen with temperature, rainfall and vegetation. If you see "Greek" in a climate question, think "three temperature zones."