Oh sorry but this isnt english so i cant help with this u shouldnt have clicked history
D. That all aspects of the piece should work together to create a certain effect
To create a "unity of effect" on the reader, it should have a certain effect on the reader. Like a really sad and depressing book should not exactly make the reader sad, but to feel the parts of the book that spoke out to the reader.
Wool is warm, but synthetic fibers are more water resistant.
This sentence is correct.