Step 1: Recall how cyclones get power.
Tropical cyclones form over warm seas and draw their energy from heat exchange between the ocean and the air.
Step 2: Check Statement-I.
The energy comes from latent heat released when warm, moist sea air rises and its vapour condenses, not from cold air. So Statement-I is incorrect.
Step 3: Check Statement-II.
Once a cyclone moves over land or away from the warm sea, it loses its moisture supply and steadily weakens. So with greater distance from the sea its force decreases, making Statement-II correct.
Step 4: Combine the findings.
Statement-I is wrong and Statement-II is right.
Step 5: Match the option.
This fits the choice that only Statement-II is correct.
Step 6: Conclude.
Only statement-II is correct.
\[ \boxed{\text{Only statement-II is correct}} \]