Given:
The triangle ABC rotated 270 degrees clockwise.
The rule of rotation is

To find:
The coordinates of point B after the given rotation.
Solution:
From the given graph, it is clear that the coordinates of point B are (4,4).
The given rule of rotation is:

Using this rule, we get

The coordinates of point B after the given rotation are (-4,4).
Therefore, the correct option is C.