(A) $BeC{l}_2$ is covalent whereas  $BaC{l}_2$ is ionic.
(R) Smaller is size of the cation, greater is the polarising power.

If both (A) and (R) are correct but (R) is not the correct explanation of (A)

If both (A) and (R) are correct and (R) is the correct explanation of (A)

If (A) is correct but (R) is not correct

If (A) is incorrect but (R) is correct