A __________ is a variable that receives an argument which is passed to a module.

Write a stub for the following function prototype:

``` double root( double a, double b, double c, int i); // Precondition: a != 0 and a, b, c are coefficients of // a quadratic equation a*x*x + b*x + c = 0 The value // of i is either +1 or -1 to choose which root. // Postcondition: return value, x, satisfies the // equation a*x*x + b*x + c = 0 ```

Similar to videos, the options for changing how the sound plays during the slide show appear on the _____ Tools Playback tab.

A. Audio B. Video C. Media D. 3D