Answer: OPTION C.
Explanation:
Observe the figure.
You can identify that the vertices of the triangle T are:

And the vertices of the triangle T' are:

You can notice that the y-coordinates of the triangle T and the y-coordinates of the triangle T' are equal, but the x-coordinates change; these are translated "k" units to the left.
You can pick the x-coordinates of the vertices
and
and write the following equation:
Solving for "k", you get:

Therefore, the translation from T to T' is 5 units left.