Green is cited for contempt of the House of Representatives after she refuses to answer certain questions posed by a House Committee concerning her acts while serving as a United States Ambassador. A federal statute authorizes the Attorney General to prosecute contempts of Congress. Pursuant to this law, the House directs the Attorney General to begin criminal proceedings against Green. A federal grand jury indicts Green, but the Attorney General refuses to sign the indictment."Which of the following best describes the constitutionality of the Attorney General's action?
Illegal, because the Attorney General must prosecute if the House of Representatives directs.   Illegal, because the Attorney General must prosecute those who violate federal law.  Legal, because ambassadors are immune from prosecution for acts committed in the course of their duties.  Legal, because the decision to prosecute is an exclusively executive act