Answer:
Option C
Explanation:
IV is the converse of the first premise and so it holds.
II is the converse of the third premise and so it holds.
Some fruits are flowers. No flower is a boat.
Since one premise is particular and one negative, the conclusion must be particularly negative and should not contain the middle term. So, it follows that 'Some fruits are not boats'.
No flower is a boat. All boats are rivers.
Since the middle term is distributed twice, the conclusion cannot be universal. Again since one premise is negative, the conclusion must be negative and shouldn't contain the middle term. So, it follows that 'Some flowers are not rivers' Thus, only II and IV follow. Hence, the answer is (c)