Which sentence contains a nonrestrictive clause that is punctuated correctly?

Kafka originally referred to gregor's parents as “the mother” and “the father”. however, the translator refers to them as “his mother” and “his father”. why might the translator use “his” instead of “the”? a. the word “his” makes the story smoother to read in english. b. the word “his” allows gregor’s parents to become more central characters. c. the word “his” makes gregor’s parents sound less loving. d. the word “his” creates a more negative tone.