Answer: D. Either Linda or Dennis, but not both.
Explanation: AGI stands for adjusted gross income. This is basically your gross income which is adjusted after tax deduction.
In this case, because the house is shared between Linda and Dennis and also since they are the ones who earn only. Therefore, either one of them would be eligible for earned income tax credit.
If they had been living in separated houses, both of them would have received the earned income Tax Credit.