The formula to find the rate of simple interest is:
[tex]r = (1/t)(A/P - 1)[/tex]
Let's plug in the values...
[tex]r = (1/3.5)((4783.25/3800) - 1) = 0.07392857[/tex]
[tex]r = 0.07392857[/tex]
Let's convert that to a percentage...
[tex]R = 0.07392857 * 100 = 7.3929[/tex]
The answer would be C!
Have a nice day! :)