Classify the sentence based on content: is it a fact, an opinion, or a general statement?
Clean energy is the future.
The sentence "Clean energy is the future" is an opinion.
Complete the following task based on the instruction and optional input provided.### Instruction:
Classify the sentence based on content: is it a fact, an opinion, or a general statement?

### Input:
Clean energy is the future.

### Output:
The sentence "Clean energy is the future" is an opinion.