Which of the following is TRUE regarding the experiment with Paramecium and the Congo-red stained yeast? (Choose all that apply)
a) Congo red is a pH indicator that turns from red to blue as pH increases.
b) As the paramecium digests the yeast, the pH of the vacuole/lysosome decreases.
c) The food vacuoles/lysosomes will change color over time from blue to red.