A steel ball is released from rest relative to the ground from a height of 2.0m in a laboratory where g=9.8m/s2. At the same instant, an elevator cab passes the window moving upward at a constant 3.0m/s. Ignoring air resistance, what acceleration does an observer inside the elevator measure for the falling ball?
a) 12.8m/s2 downward
b) 9.8m/s2 upward
c) 9.8m/s2 downward
d) 6.8m/s2 downward