Final answer:
The equation of the line with a slope of 4 and a y-intercept of 12 is y = 4x + 12.
Step-by-step explanation:
The equation of the line with a slope of 4 and a y-intercept of 12 can be found using the slope-intercept form of a linear equation, which is y = mx + b, where m is the slope and b is the y-intercept.
Given that the slope is 4 and the y-intercept is 12, the equation of the line would be y = 4x + 12.
Therefore, the correct answer is y = 4x + 12 (option D).