The given question is based on ratios and percentages. We are given that the ratio of the number of boys to girls in a school is 3:2. Additionally, we are given that 20% of the boys and 30% of the girls are scholarship holders. We need to find the percentage of students who are not scholarship holders.

To solve this question, we can follow the steps below:

1. Assume a certain number for the total number of students in the school. Let's assume there are 5 units in the ratio, which represents a total of 5x students.

2. According to the given ratio, the number of boys would be 3 units and the number of girls would be 2 units. So, the number of boys is 3x and the number of girls is 2x.

3. Now, we need to find out how many boys and girls are scholarship holders. We know that 20% of the boys are scholarship holders, so the number of boys who are scholarship holders is 20% of 3x, which is (20/100) * 3x = 0.6x. Similarly, 30% of the girls are scholarship holders, so the number of girls who are scholarship holders is (30/100) * 2x = 0.6x.

4. To find the total number of scholarship holders, we add the number of boys who are scholarship holders to the number of girls who are scholarship holders: 0.6x + 0.6x = 1.2x.

5. Now, we need to find the percentage of students who are not scholarship holders. The total number of students in the school is 5x, and the total number of scholarship holders is 1.2x. So, the number of students who are not scholarship holders is 5x - 1.2x = 3.8x.

6. Finally, we can calculate the percentage of students who are not scholarship holders by dividing the number of students who are not scholarship holders by the total number of students and multiplying by 100: (3.8x / 5x) * 100 = 76%.

Therefore, the percentage of students who are not scholarship holders is 76%. Hence, option D is the correct answer.