To find the difference between 1,230 and 199, we subtract 199 from 1,230. When we subtract, we start from the rightmost digit and work our way left. In this case, 0 minus 9 is -9, which we cannot do without borrowing. So, we borrow 1 from the thousands place, making it 10. Now, 10 minus 9 is 1, and we write down 1 in the ones place. Moving to the next column, 2 minus 9 is -7, again requiring borrowing. We borrow 1 from the hundreds place, making it 1. Now, 11 minus 9 is 2, and we write down 2 in the tens place. Finally, 1 minus 1 is 0, and we write down 0 in the hundreds place. Therefore, the correct answer is 1,131.