The inability to stop thinking about a particular idea or topic is referred to as Obsessive behavior. Obsessive thoughts are persistent and intrusive, often leading to anxiety or discomfort. People experiencing obsessive behavior may feel compelled to repeatedly focus on a specific idea, unable to divert their attention. This is a key feature of Obsessive-Compulsive Disorder (OCD).
Step 1: Analyze the options.
(A) Impulsive behavior: Impulsivity refers to acting without forethought or planning, which is not about obsessive thinking.
(B) Obsessive behavior: This is the correct term for the inability to stop thinking about a particular idea or topic. It involves intrusive thoughts.
(C) Compulsive behavior: Compulsive behavior refers to repetitive actions or rituals that a person feels driven to perform, often as a response to obsessive thoughts. While related, it refers to behavior, not thinking.
(D) Hyperactive behavior: Hyperactivity refers to excessive activity or energy levels, which is not related to thinking patterns or obsession.
Step 2: Conclusion.
Obsessive behavior is the most accurate term for the condition described, making (B) the correct answer.
Final Answer:
\[
\boxed{(B) \, \text{Obsessive behavior}}
\]