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 tubes are pipes.

All switches are pipes.

All pipes are boards.

Conclusions:

I. All switches are boards.

II. All boards are tubes.

III. Some boards are switches.