The correct answer is worry about.
A. worry about
The correct answer is (A) To worry about; to meditate on or over (esp. insults, ill designs, etc.) to think about sullenly, particularly after a perceived insult or injury.
To focus on a subject silently and obsessively.
Brood comes from Old English brod, Danish broed, German brut.
Examples of use:
- He was inclined to brood excessively over his apparent grievances.
- She brooded over the problem for days.