Correct option is A
Option (a) is the correct meaning of the given idiom.
Have a bee in your bonnet: Meaning of idiom: To be preoccupied or obsessed with something, often in an anxious or angry way.
Meaning in context: The idiom refers to someone who is constantly thinking about or is fixated on a particular issue, often to the point of obsession.
Example 1: "She has a bee in her bonnet about the environment and won’t stop talking about recycling."
Example 2: "He’s got a bee in his bonnet about his diet and won’t eat anything that isn’t organic."