To find the perimeter of a triangle you simply add up all the sides. Because your possible answers are in fractions, I would convert the decimal values into fractions.
2.2 becomes 2 & 1/5
3.25 becomes 3 &1/4
1 & 5/6 is already a fraction, so you can leave it as it is. To combine these you need to find a common denominator (here it is 60). *It may help to convert the mixed numbers to improper fractions to add them, which is what I did*
You get:
132/60 + 110/60 + 195/60
When you add all that up you get 437/60, which is 7&17/60, so D
I know that was long and wordy, but I hope I helped!!