Choose the correct statements from the following:
$(I)$ In vapour phase $BeCl_2$ exists as a chlorobridged dimer.
$(II)$ $BeSO_4$ is readily soluble in water.
$(III)$ $BeO$ is completely basic in nature.
$(IV)$ $BeCO_3$ being unstable, is kept in an atmosphere of $CO_2$.
$(V)$ $BeCO_3$ is the least soluble among all the carbonates of group $2$ elements.

• A
  $II, III, IV$
• B
  $I, II, IV$
• C
  $I, IV, V$
• D
  $II, III, V$