Statements: No herb is a tree.
Some trees are shrubs.
No shrub is petal.
Conclusions: I. No petal is a shrub.
II. Some shrubs are not herbs.
III. No tree is a petal.
No shrub is petal(E) ⇒ Conversion ⇒ No petal is a shrub(E). Hence, conclusion I follows. No herb is a tree(E) + Some trees are shrubs(I) ⇒ Some shrubs are not herbs(O*). Hence, conclusion II follows. Some trees are shrubs(I) + No shrub is petal(E) ⇒ Some trees are not petals(O). Hence, conclusion III does not follow