Which of the following sentences contain a comma error ?

Which sentence best states a theme of gilman's "the yellow wallpaper"? a. women in the 19th century often played a lesser role in marriage. b. when a person is unwell, rest is the best medicine. c. a husband does not believe that his wife is sick, which leads to disastrous consequences. d. the narrator does not like the yellow wallpaper in her bedroom and becomes mentally disturbed.