Attorney Chen previously served as a government lawyer and was substantially involved in the drafting and negotiation of a major environmental protection treaty between the United States and several foreign nations. After leaving government service, Attorney Chen joins a private law firm. A few years later, a private energy company seeks to challenge the interpretation of a specific clause within that same environmental treaty, and they approach Attorney Chen's new firm for representation. Can Attorney Chen or her new firm represent the energy company in this matter?

1. AYes, if Attorney Chen is screened from the matter and does not share in any fees generated from it, and written notice is promptly given to the appropriate government agency.
2. BYes, because drafting a treaty is a general government function, not a specific 'matter' for conflict purposes.
3. CNo, unless the government agency provides informed consent, confirmed in writing.
4. DNo, because Attorney Chen's prior substantial involvement with the treaty constitutes a conflict of interest, which is imputed to her entire firm.