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:
Some hills are mountains.
Some hills are valleys.
All valleys are rivers.
Conclusions:
I. Some rivers are valleys.
II. Some mountains are valleys.
III. Some hills are rivers.