What effects do acids and alkalis have on indicators such as litmus, methyl orange, and phenolphthalein?
a. They change the color of litmus to red in the presence of acids and blue in the presence of alkalis.
b. They turn methyl orange from red to yellow in the presence of acids and from yellow to red in the presence of alkalis.
c. They cause phenolphthalein to turn pink in the presence of acids and remain colorless in the presence of alkalis.
d. They have no effect on the indicators.
