The equation y = -4.9x^2 + 9.8x + 2 models the trajectory of a ball thrown in the air by a man, where y = the distance the ball is from the ground in meters and x = the elapsed time in seconds. What is the greatest distance the ball is from the ground?
a) 2.2 meters
b) 9.8 meters
c) 6.9 meters
d) 4.9 meters