The correct answer is: B. behind, in
The word “behind” indicates a location that is to the rear of something. The word “in” indicates a location that is inside something. In this case, the speaker is asking if the listener looked for the lost item behind the door or inside the cupboard.
The other options are incorrect because they do not accurately describe the location of the lost item. Option A, “under, behind,” is incorrect because the word “under” indicates a location that is below something, while the word “behind” indicates a location that is to the rear of something. Option C, “in, over,” is incorrect because the word “in” indicates a location that is inside something, while the word “over” indicates a location that is above something. Option D, “at, in,” is incorrect because the word “at” indicates a location that is near something, while the word “in” indicates a location that is inside something.