The answer to this is letter D. This is a question that can be answered better when you can see the charts. Charts are actually used in order to help people visualize the numbers that are being shown to them. Can you imagine if there are no charts that are shown? You may find it complicated to compute the number of non-US residents that can be seen in the charts. According to the instructions, the percentages have already been rounded off to the nearest whole number as this can make it easier for people to understand. You need to use simple mathematical equations in order to get the answer.