Answers: choice C and choice E
Plugging x = 3 and y = -1 into both equations of choice C lead to a true result (the same number on both sides). This is why the system of equations listed in choice C is one possible answer. Choice E is a similar story.
If your teacher didn't mean to make this a "select all that apply" type of problem, then it's likely your teacher may have made a typo.
