Which two of the following statements are accurate regarding heterotrophs?
a. Amino acids may be a good carbon source for a heterotroph.
b. Nucleic acids (DNA and RNA) cannot be used as carbon sources.
c. Heterotrophs can use the carbon in ₂ as a growth substrate.
d. The genus Pseudomonas is noteworthy because its cells metabolize only glucose as a carbon source.
e. Some heterotrophs are restricted to just a few carbon substrates.