Apreviously healthy 35-year-old woman presents to your clinic with questions about breast cancer screening. she has no family history of breast cancer and wants to know when she should start screening. per the united states preventive services task force, which of the following is the most appropriate next step in management? a) initiate screening mammography at age 50 b) initiate screening magnetic resonance imaging at age 40 c) initiate screening mammography at age 40 d) initiate screening ultrasound at age 50