The Sun is the primary source of energy for the Earth. It provides energy through sunlight, which drives weather patterns, ocean currents, and supports all forms of life through photosynthesis.
Step 1: Analyzing each option.
- (A) Wind: Incorrect. Wind energy is derived from solar energy, but it is not the primary source.
- (B) Sun: Correct. The Sun is the ultimate source of energy for life on Earth, driving weather and ecosystems.
- (C) Fossil fuels: Incorrect. Fossil fuels are derived from ancient biological material, which ultimately comes from the Sun.
- (D) Water: Incorrect. Water is essential for life, but it is not the primary source of energy for the Earth.
Step 2: Conclusion.
Thus, the correct answer is (B), the Sun.
Final Answer:} Sun.