Correct option is C

Some fruits are trees and no tree is a bird, so those fruits (which are trees) cannot be birds. Hence, we cannot say some birds are fruits.
Conclusion I does not follow.
Conclusion II: No fruit is flower.
(There is no any direct relation between fruit and flower)
Conclusion II follows.
Conclusion III: Some flowers are trees.
Flowers are birds, and no tree is a bird. Hence, flowers cannot be trees at all.
Conclusion III does not follow.
So, No conclusion follows.
Thus, correct option is (c).