Answer:
B yellow
Step-by-step explanation:
As you may already know most animals breathe oxygen and exhale carbon dioxide. This is no different in snails. If the carocals were dipped into bromothymol blue-containing cups that allowed the snails to breathe, they would produce a large amount of carbon dioxide in all, within 24 hours. Carbon dioxide causes bromothymol blue to turn yellow due to the chemical reactions that occur between its molecules. So we can say that after 24 hours, the bromothymol blue would turn yellow.