Read the given statements and conclusions carefully. You have to take the given statements to be true even if they seem to be at variance from commonly known facts and decide which conclusion(s) logically follow(s) from the given statements.
Statements:
Some trees are flowers.
All flowers are leaves.
Conclusions:
(I) All leaves are trees.
(II) All flowers are trees.

Statements:
Some trees are flowers.
All flowers are leaves.
From the given information Venn Diagram will be: 

​Conclusions:
(I) All leaves are trees. Not follow All leaves are not trees, but some tress are leaves that's why it is not followed.
(II) All flowers are trees. Not follow All flowers are not trees but some flowers are trees that's why it is not followed.

Thus, the correct option is (a) Neither conclusion (I) nor (II) follows.