This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Breast, Subject name: Surgery
Risk factors for the development of breast cancer include all of the following EXCEPT 
Select and explain. 
A. Early menarche, B. Nulliparity, C. Late menopause, D. Longer lactation period
D: Longer lactation period
Answer: D: Longer lactation period 
Explanation: Increased exposure to estrogen is associated with an increased risk for developing breast cancer, whereas reducing exposure is thought to be protective. Correspondingly, factors that increase the number of menstrual cycles, such as early menarche, nulliparity, and late menopause, are associated with increased risk. Moderate levels of exercise and a longer lactation period, factors that decrease the total number of menstrual cycles, are protective.