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 follows from the statements.

Statements:
All cats are birds.
Some tigers are cats.
All bees are tigers.

Conclusions:
I. All bees are birds.
II. Some bees are birds.
III. Some birds are tigers.
IV. All tigers are birds.