Phenol red is a chemical that turns red when carbon dioxide, co2, is absent and yellow when co2 is present. a small, green plant seedling is placed in phenol red in the dark. which one of the following is most likely to occur?

if the solution is yellow to begin with, it will turn red because respiration is occurring.
if the solution is red to begin with, it will remain red because respiration is occurring
if the solution is red to begin with, it will turn yellow because respiration is occurring.
if the solution is yellow to begin with, it will turn red because photosynthesis is occurring.
if the solution is red to begin with, it will turn yellow because photosynthesis is occurring.