The answer would be B. Let's say Katrina's father was 10 inches tall. Subtract 2 inches to measure Katrina's mother's height, subtract another 2 inches to measure Katrina's height. Finally, subtract another 2 inches to measure Katrina's brother's height. Add all the negative 2s together in order to get -6. That is the difference between Katrina's father's height and her brother's height.