Total assignments = 5
The average grade received in the first 2 assignments = 75
This means the sum of the first 2 assignments = 75 * 2 = 150
Torry wishes to receive an average grade of 90 for all the 5 assignments
This means the sum of the 5 assignments must be at least = 90 * 5 = 450
Total points needed from the remaining 3 = 450 - 150 = 300, this will be an average of 300/3 = 100 points per assignment

Torry's present average = 75
So, Torry is short of 100 - 75 = 25 points i.e he will need 25 more points on the average of the remaining 3 assignments
% needed on the remaining assignments = $$\frac{25}{75}\cdot\frac{100}{1}=33.3\%\ or\ 33\frac{1}{3}\%$$

The average grade for Torry's remaining assignments must be 33.3% greater than the average grade for the assignment he has already submitted.

Answer = D