The third one its already in order
In order to visualize the transformations, we must execute the transformation in the options
The first transformation would shift triangle ABC 3 units to the left and reflect it across x = 4. This will not map ABC unto DEF.
The second transformation would shift triangle ABC 7 units down and reflect it across x =4. This will map ABC unto DEF,
So, the answer is the second option.
I believe it is an exponential function.