某溶液中大量存在四种离子：NO^-₃、SO^2-₄、H⁺、M，其物质的量之比为：N(NO^-₃):n(SO^2-₄):n(H⁺):n(M)=3:1:3:1，则M可能为                                                              （   ）
①Fe²⁺                                                                ②Mg²⁺                                                ③Cl^—                                                   ④Ba²⁺

A：①②④

B：③

C：②

D：①②