Step 1: Polluter Pays Principle (Statement I).
The polluter pays principle makes the polluting party bear the cost of managing pollution to prevent environmental damage.
It is recognized in international and Indian environmental law.
Hence, Statement I is correct.
Step 2: Precautionary Principle (Statement II).
The precautionary principle advises taking preventive action in the face of uncertainty.
It requires caution, prior review, and pausing before carrying out innovations that may pose risks to human health or the environment.
Thus, Statement II is correct.
Step 3: Application by policymakers (Statement III).
This principle is indeed applied when scientific evidence is insufficient but potential harm is serious or irreversible.
Policymakers use it to delay or modify risky actions.
Hence, Statement III is also correct.
Therefore, all three statements are correct.
Final Answer:
\[
\boxed{\text{(B) I, II and III are correct}}
\]