GKFix MCQ Question

What is the correct equation for the first ionization enthalpy of element X?

• A. X(s) → X⁺(s) + e⁻
• B. X(g) → X⁺(g) + e⁻
• C. X⁺(g) → X²⁺(g) + e⁻
• D. X(l) → X⁺(l) + e⁻