The +3 without the presence of a bracket tells us that a vertical translation of 3 units upward has been applied to the parent graph. If you look at the picture you can see that the red graph has moved up 3 units from the origin.
If the 3 were to be inside a bracket, it would indicate that there has been a horizontal translation either left or right. The graph has not moved horizontally therefore none of the options with the brackets are correct.
