According to the chart, the number of people between 50 and 60 points is 4; The number of people aged 60 to 70 is12; The number of people between 70 and 80 points is14;

The number of people between 80 and 90 points is 8; The number of people between 90 and 100 is 2.

The number of people who scored between 70 and 80 points was the highest; The number of people who scored between 90- 100 was the least; The total number of people is 4+12+14+8+2 = 40;

If the score is not less than 60, it is qualified, and the passing rate of this class is (12+14+8+2) ÷ 40 = 90%.

So choose D.