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.
I agree with the person above - although this wouldn't be my first thought when I hear the word empower, among these answers, the one that seems the most correct is A. to create a strong desire or longing.
For example:
The desire to go home empowered me.
Answer:
The bus was stopped by them
