You are answering a USMLE-style medical question. Question: A 35-year-old woman presents with severe fear reactions to seeing dogs after moving into a new suburban neighborhood. She states that she has always had an irrational and excessive fear of dogs but has been able to avoid it for most of her life while living in the city. When she sees her neighbors walking their dogs outside, she is terrified and begins to feel short of breath. Recently, she has stopped picking up her children from the bus stop and no longer plays outside with her children in order to avoid seeing any dogs. Which of the following would be the best definitive treatment for this patient? Options: A) Selective serotonin reuptake inhibitors (SSRIs) B) Short-acting benzodiazepines C) Systematic desensitization D) Cognitive behavioral therapy Reply with ONLY the letter of the correct answer (A, B, C, or D). No explanation.