Two sections of an aquatic plant were put into two separate test-tubes, P and Q. Each test-tube had hydrogencarbonate indicator in it and was sealed, then left at $20\degree\text{C}$. Test-tube P was placed in the light, whereas test-tube Q was placed in the dark. The table shows how carbon dioxide affects the colour of the hydrogencarbonate indicator. What colour would the indicator have after 12 hours?
- AP: dark red, Q: orange
- BP: dark red, Q: dark red
- CP: orange, Q: dark red
- DP: orange, Q: orange