To answer this question we can propose the following equation:
[tex]d=750 -x(67)[/tex]
Where:
x is the number of weeks elapsed.
d is the debt depending on the weeks.
Robert promised to pay at least $ 67 each week.
Therefore, after 5 weeks the debt of rober should be:
[tex]d\leq750-5*67[/tex]
[tex]d\leq415[/tex]
Then scenario A) is possible because [tex]150<415[/tex].
After 6 weeks:
[tex]d\leq750-6*67[/tex]
[tex]d\leq348[/tex]
Then scenario B) is possible because [tex]200<348[/tex].
After 7 weeks
[tex]d\leq750-7*67[/tex]
[tex]d\leq281[/tex]
Then scenario C) is possible because [tex]250 <281[/tex].
After 8 weeks
[tex]d\leq750-8*67[/tex]
[tex]d\leq214[/tex]
So scenario D) is NOT possible because [tex]300>214[/tex]
Finally the correct answer is option D.