Excerpt from the haunted man
wiki

2 redlaw is a teacher of chemistry who often broods over wrongs done him and grief from his past.

3 he is haunted by a spirit, who is not so much a ghost as redlaw's phantom twin and is "an awful likeness of his features, and his bright eyes, and his grizzled hair, and dressed in the gloomy shadow of his " this specter appears and proposes to redlaw that he can allow him to "forget the sorrow, wrong, and trouble you have cancel their " redlaw agrees. however, before the spirit vanishes it imposes an additional consequence: "the gift that i have given you, you shall give again, go where you will."

what is the meaning of the verb broods as it is used in section 2?
2 redlaw is a teacher of chemistry who often broods over wrongs done him and grief from his past.
a) fondly acknowledge a significant event
b) feel or express violent, uncontrollable anger
c) think deeply about something that makes one unhappy
d) put out of one's mind; cease to think of or consider