On a coordinate grid, one unit on the x-axis represents 2 actual units while one unit on the y-axis represents 1 actual unit. A straight line passes through the plotted points P(1,2) and Q(4,5) as read from that grid. Which of the following is the equation of the line in actual coordinate units, expressed in slope–intercept form?
a) y=21x+23
b) y=x+1
c) y=21x+1
d) y=21x+2