Consider the following statements int numl, num2, num3: double length, width, height; double volume; num1 = 6; num2-7; num3 = 4; length 6.2: width 2.3; height 3.4 and the function prototype: double box (double, double, double) Which of the following statements are valid? If they are inv explain why. (4) a. volume - box (length, width, height) b. volume=box (length, 3.8, height); c. cout