$CO_2$ is a non-polar molecule $(\mu = 0)$ whereas $SO_2$ is polar $(\mu = 1.62 \ D)$. This difference is due to the fact that:

• A
  $C$ and $O$ have approximately the same electronegativity while $S$ and $O$ have different electronegativities
• B
  $CO_2$ has an even number of double bonds whereas $SO_2$ has an odd number of double bonds
• C
  $C$ and $O$ are in different groups whereas $S$ and $O$ are in the same group
• D
  $CO_2$ is linear whereas $SO_2$ is not linear.