What is a necessary criterion for participants to trade on FGX?

The correct answer highlights the importance of registration and compliance with regulatory requirements for participants wishing to trade on the Japan First Gulf Exchange (FGX). Engaging in trading activities on any exchange typically necessitates that participants not only sign up formally but also adhere to the rules and regulations set forth by the exchange's governing authorities. This ensures that all trading practices are conducted in a legal and transparent manner, providing a framework that protects both the investors and the integrity of the market.

Meeting regulatory requirements also encompasses aspects such as appropriate checks on the financial background of traders, thus reducing the risk of fraud and promoting fair trading. By requiring registration and compliance, the FGX fosters a secure environment for both novice and experienced traders, enabling a more efficient marketplace.

The other choices do not encapsulate the essential criterion as effectively. For instance, while having trading experience, belonging to an approved financial institution, or maintaining a high credit score may be beneficial attributes for individual traders or organizations, these alone do not fulfill the fundamental requirement for participation in trading on the FGX. The emphasis on registration and regulatory compliance is paramount to facilitating a structured and reliable trading atmosphere.