The sum of the graph is 29
The questions ask what is the probability of getting an 8-10
You look at the graph and infer that getting an 8-10 has a frequency of 11
So, 11/29 is the probability of getting a sum of 8-10
So you answer is option c
I believe a, b, and d is to be an effective persuasive strategy; believe the speaker to speak truth, and we are willing to listen to the statistics