Equation would be: 250 + 100x
where, x = number of car sold,
So, when x = 1, it would be: 250 + 100(1) = 250+100 = 350
When x = 4, it would be: 250 + 100(4) = 250+400 = 650
when x = 5, it would be: 250 + 100(5) = 250+500 = 750
You can see the answers are matching with option D. So, Your Final answer would be option D
Hope this helps!