I would say D. There is no logical explanation for the final answer but there is for everything else.
For A: Makes sense because 3x-2 are in parenthesis outside a number so you can multiply.
For B: Makes sense because you are allowed to add/subtract like terms but in this case only subtracting would make sense, (which is what they did) since you want to get all the like terms on one side.
For C: Makes sense because you are trying to simplify the equation, and they are both like terms (they are both numbers that have no letter attached to them) and they are on the opposite side making them able to be simplified.
If a question has four possible answers, and you are strictly guessing regarding which of them is correct, then the chances of your choosing the correct one from the four is 1 in 4, or 0.25.