Which of the following characteristics differentiates an autotroph from a heterotroph?

A. A heterotroph can only obtain its energy from an autotroph.
B. An heterotroph can only obtain its energy from a heterotroph.
C. An heterotroph must obtain its energy from a heterotroph or other autotroph heterotrophs only obtain their energy from the Sun.
D. A heterotroph must obtain its energy from a autotroph or other heterotroph. Autotrophs only obtain their energy from the Sun.