. The elevations, in feet, of three cities are marked on the number line shown below. City P 10 5 City Q 0 -5 -10 -15 City R-20 -25 -30 The point O on the number line represents sea level. Which statement must be true? A. City P and City Q are above sea level. B. City Q and City R are below sea level. C. City P is above sea level and City Q is below sea level. D City P is above sea level and City R is below sea level