ANSWER and EXPLANATION
We want to transform the graph and find the transformations needed to obtain the graph:

When a function is transformed as follows:

it implies that the function has been shifted vertically upwards by "a" units.
Hence, a transformation of:

implies that to obtain the graph of g(x), we have to shift the graph of f(x) by 1 unit upwards.
Let us show this on the graph:
Hence, the transformation needed in order to obtain the graph of g(x) from the graph of f(x) is a vertical shift.