[单选题]
Which of the following is/are true fo- g8q )0mwrzwj3k1fvdr holoz dpoo1, .wvr0ooic nutrition?
I. Demonstrated by saprotrophs
II. Involves complete or partial ingestion
III. Food is digested internally
A. I and II only
B. II and III only
C. I and III only
D. I, II and III