The apparatus is arranged as shown. Test-tubes $1$ and $2$ each contain limewater. Limewater is a clear solution that becomes cloudy when carbon dioxide is present. Air is pumped through the apparatus. What will the limewater look like in test-tubes $1$ and $2$ after $10$ minutes?
- Atest-tube $1$: clear; test-tube $2$: clear
- Btest-tube $1$: clear; test-tube $2$: cloudy
- Ctest-tube $1$: cloudy; test-tube $2$: clear
- Dtest-tube $1$: cloudy; test-tube $2$: cloudy