On heating which of the following releases ${\text{CO}}_2$ most easily?

Thermal stability of carbonates increases as the size of the cation increases and its polarizing power decreases.Alkali metal carbonates (${\text{K}}_2{\text{CO}}_3,{\text{Na}}_2{\text{CO}}_3$) are very stable and do not decompose easily.For alkaline earth metals, stability increases down the group: ${\text{MgCO}}_3<{\text{CaCO}}_3<{\text{SrCO}}_3<{\text{BaCO}}_3$.${\text{Mg}}^{2+}$ has the smallest size and highest polarizing power among the given options, making ${\text{MgCO}}_3$ the least stable. It releases ${\text{CO}}_2$ at the lowest temperature:
$${\text{MgCO}}_3\stackrel{\Delta }{\to }\text{MgO}+{\text{CO}}_2$$