PRACTICAL HELP

[withez]

Hello
I am having a hard time explaining some prac results I got in class and I was hoping I could have some help from you brainiacs.
I can kind of get the first three, but I have no CLUE why Vial D was pink-red.
Just some background info:

• Red= 6.2-8.2 pH Yellow= <6.2 pH Pink= >8.2 pH
• The Alginate balls contain bakers yeast, which respires anaerobically. When they respire, they produce carbon dioxide which makes the solution they are in acidic

These are the results everyone had.
I have attached the method and my results.
Many thanks