JEE Main Chemistry question

Solubility product of MX₂ at 298 K is 4×10⁻¹². At this temperature concentration of M²⁺ ion in mol per litre is:

• (A)2×10⁻⁶ M
• (B)1×10⁻⁴ MCorrect
• (C)1.6×10⁻⁴ M
• (D)4×10⁻⁶ M