in a class of 20 students, 2 students have a grade of d, 8 students have a grade of c, 6 students have a…

Explanation:

Step1: Calculate total number of students

$2 + 8+6 + 4=20$

Step2: Calculate probability of grade D

$P(D)=\frac{2}{20}=0.1$

Step3: Calculate probability of grade C

$P(C)=\frac{8}{20}=0.4$

Step4: Calculate probability of grade B

$P(B)=\frac{6}{20}=0.3$

Step5: Calculate probability of grade A

$P(A)=\frac{4}{20}=0.2$

Answer:

The correct probability - distribution has probabilities 0.1 for D, 0.4 for C, 0.3 for B and 0.2 for A. So the bar - chart with these heights for D, C, B and A respectively is the correct one. Without seeing the full options clearly (since the image has some issues), but based on calculations, the bar for D should be at 0.1, C at 0.4, B at 0.3 and A at 0.2 on the vertical axis.