Three statements are given followed by three conclusions numbered I, II and III. Assuming the statements to be true, even if they seem to be at variance with commonly known facts, decide which of the conclusions logically follow(s) from the statements.

Statements:
All cows are mammals.
All donkeys are mammals.
All mammals are animals.

Conclusions:
I. All donkeys are animals.
II. All animals are donkeys.
III. Some cows are donkeys.