Consecutive integers are like 1, 2, and 3. They are in a row. Think about plugging numbers in for x. 1 and 1+2 are not consecutive, so A is not the answer. B and C don't start with x, so they aren't the answer. That leaves D, because it starts with x, then goes to x+1, and then to x+2. These are consecutive, because if x was 1, it would be 1, 2, 3.
