The equation d = 420 - 65t represents a line in slope-intercept form (y = mx + b), where d is the dependent variable (y), t is the independent variable (x), the slope (m) is -65, and the y-intercept (b) is 420.
To find the d-intercept (the point where the line crosses the y-axis), we can substitute t = 0 into the equation and solve for d:
d = 420 - 65(0)
d = 420
Therefore, the d-intercept of the line is (0, 420).
So the answer is (a) (0, 420).