Klinfelters syndrome is when there is an extra X chromosome in males.
So instead of the normal sex chromosomes for males (XY), a male with klinefelters syndrome will have XXY.
I have included a pic of the karyotype to give you a better idea of what I'm talking about.
Hope this helps! I'm happy to help with any other questions you might have :)
Dr. Blackwell caused rats to stop breathing when he lesioned their MEDULLA.
When doctor Blackwell induced a lesion in the rats' medulla, he discovered that the rats stopped breathing. He explained this observation by saying that the medulla has functional role to play in the breathing process of rats.
I'd go with A. can interact to influence a trait, such as eye color