Three statements are given, followed by four conclusions numbered I, II, III and IV. 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 birds are ducks.

Some ducks are crows.

All crows are parrots.

Conclusions:

I. Some parrots are birds.

II. Some parrots are ducks.

III. Some crows are birds.

IV. All parrots are birds.