Analogy: Motorcycle is to Battery as Life is to ____. Choose the energy source or essential power analogue, within each domain.

Introduction / Context:
Energy-source analogies map a system to its key power source. A motorcycle uses a battery (for ignition/electricals) alongside fuel; the battery is the essential electrical power source. We must find the macro analogue for “life.”

Given Data / Assumptions:

• Motorcycle ↔ battery as immediate electrical source.
• Life on Earth ↔ primary external energy driver.
• Options are celestial bodies, only one of which is the principal energy provider.

Concept / Approach:
The Sun is Earth’s principal energy source driving photosynthesis, climate, and energy flows that sustain life. Thus “life : sun” mirrors “motorcycle : battery.” Comet and moon are not primary energy sources; “star” is generic, while the specific star that powers Earth-life is the Sun.

Step-by-Step Solution:
Identify the “power source” in each domain.Select the specific star (Sun) rather than a generic class.

Verification / Alternative check:
Energy-flow reasoning: solar radiation underpins ecosystems; the moon reflects sunlight and affects tides but is not an energy source for life’s metabolism.

Why Other Options Are Wrong:
Comet: negligible contribution. Star (generic): imprecise; the correct specific is the Sun. Moon: not a power source.

Common Pitfalls:
Choosing “star” due to category match; specificity matters as it did for “battery” vs “power supply” in the first pair.

Final Answer:
Sun.