The Colorless Molecule O-Nitrophenyl Galactoside (ONPG) Can Be Used as an Artificial

The colorless molecule o-nitrophenyl galactoside (ONPG) can be used as an artificial substrate in assays of $\beta$ -gal in E. coli extracts. Which of the following statements is NOT true with respect to the use of ONPG?

A) Hydrolysis of ONPG by $\beta$ -gal produces yellow o-nitrophenol.
B) o-nitrophenol can be measured with a spectrophotometer.
C) Hydrolysis of ONPG by $\beta$ -gal also releases colorless galactose.
D) The o-nitrophenol moiety is blue and more suitable for use in solid media.
E) None of the above.