Arrange the following ions in increasing order of size: Na⁺, Mg²⁺, Al³⁺, O²⁻

1. A Na⁺ < Mg²⁺ < Al³⁺ < O²⁻
2. B Al³⁺ < Mg²⁺ < Na⁺ < O²⁻ Correct answer
3. C O²⁻ < Al³⁺ < Mg²⁺ < Na⁺
4. D Al³⁺ < Mg²⁺ < O²⁻ < Na⁺