Choose the correct statement on the formation of a strontium ion and the complete octet.

• A. Strontium gains two valence electrons to form Sr^2– and to achieve a complete octet in the fifth energy level.
• B. Strontium gains two valence electrons to form Sr²⁺ and to achieve a complete octet in the fifth energy level.
• C. Strontium loses two valence electrons from the fifth energy level to form Sr²⁺ and to achieve a complete octet in the fourth energy level.
• D. Strontium loses two valence electrons from the fifth energy level to form Sr^2– and to achieve a complete octet in the fourth energy level.