Answer: C. Gregor's father stands up straighter and takes better care of himself.
Gregor's father undergoes a transformation in his physical appearance just like his son. Mr. Samsa is forced to go back to work after Gregor's transformation, and ends up working as a bank messenger. He now stands very erect, dressed in a fancy, blue uniform. His eyes look brighter and his hair is combed. With the change in appearance, Mr. Samsa also gains a new sense of authority.