This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Abnormal labor, Subject name: Gynaecology & Obstetrics
A 24-year-old G2P1 woman at 39 weeks' gestation presents with painful uterine contractions. She also complains of dark, vaginal blood mixed with some mucus. Which of the following describes the most likely etiology of her bleeding 
Select and explain. 
A. Vasa pre, B. Bloody show, C. Placenta pre, D. Placenta abruption
B: Bloody show
Answer: B: Bloody show 
Explanation: Bloody show or loss of the cervical mucus plug is often a sign of impending labor. The sticky mucus admixed with blood can differentiate bloody show from antepaum bleeding. Placenta pre, placental abruption, and vasa pre are all associated with antepaum bleeding.