$A$ metal $M$ readily gives $MSO_4$, which is soluble in water. It forms its oxide $MO$ which is amphoteric. It forms an insoluble hydroxide $M(OH)_2$, which is soluble in $NaOH$ solution. The $M$ is

• A
  $Be$
• B
  $Ba$
• C
  $Ca$
• D
  $Mg$