A snowboarder starts down a frictionless, 7m-tall, 19° slope. The slope ends abruptly at the top of a 4m-high wall that has level packed snow at its base. What is the snowboarder's final speed after going down the slope and hitting the wall?
a) 10.3 m/s
b) 9.8 m/s
c) 10.7 m/s
d) 10.1 m/s