Andrea doubles as a professional pianist and a dedicated mother. She identified a few quantitative relationships and modeled them: Function | Input | Output - | - | - $A$| Duration of Andrea's practice session before a concert, $x$ | Duration of applause Andrea receives after the concert, $A(x)$ $S$ | Duration of Andrea's sleep, $k$ | Duration of Andrea's practice session before a concert, $S(k)$ $B$ | Number of times Andrea's baby wakes up at night, $r$ | Duration of Andrea's sleep, $B(r)$ **Which of the following represents the duration of Andrea's practice session before a concert as a function of the number of times her baby wakes up at night?** [[☃ radio 1]]