Which line signifies the narrator's turn from unfavorable to favorable descriptions of the “dark lady” in shakespeare's sonnet 130?
a“that music hath a far more pleasing sound”
b“my mistress' eyes are nothing like the sun”
c“my mistress, when she walks, treads on the ground”
d“and yet, by heaven, i think my love as rare”

The line that signifies the narrator's turn from unfavorable to favorable descriptions of the "dark lady" is D. "And yet, by heaven, I think my love as rare."
The other options describe her as nothing special to the author - he is saying that her voice is horrible, that her eyes are ugly, and that she walks really loudly. But the last line states that he loves her no matter what, despite her flaws of which there are many.