The complaint involves a product worth \texttt{\rupee 40,500}. As per the Consumer Protection Act, the hierarchy for complaint filing is based on the value of goods/services.
- Up to \rupee 20 lakh: District Forum
- Between \rupee 20 lakh and \rupee 1 crore: State Commission
- Above \rupee 1 crore: National Commission
Since the value of the smartphone is \rupee 40,500, Payal must file her complaint at the State Commission.
Final Answer: (B) State Commission