A 14-month-old boy presents with chronic pruritic erythematous patches on his cheeks for the past 3 months. On examination, the lesions show ill-defined borders with excoriation marks from scratching. Notably, the area marked **C** (sparing of the nose and perioral region) is unaffected. His parents report sleep disturbance due to itching. Based on the age-related pattern of presentation shown in this diagram, which of the following best explains the characteristic distribution in infantile atopic dermatitis?