7. Consider the following statements: int numl, num2, num3 double length, width, height double volume numl 61 num2 71 num341 length 6.21 width 2.3 height 3.4 and the function prototype: double box (double, double, double) 1 Which of the following statements are valid? If they are invalid, explain why. (4) a. volume box (length, width, height) b volume box (length, 3.8, height) c. cout