This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: ULTRASOUND, Subject name: Radiology
[{'content': 'Lambda sign or twin peak sign is seen in \nSelect and explain. \nA. Diamniotic Monochorionic, B. Dichorionic Diamniotic, C. Monochorionic monoamniotic, D. None of the above', 'role': 'user'}, {'content': 'Answer: B \nExplanation: The Lambda or Twin peak sign at 10-14 weeks of gestation demonstrate the high reliability of ultrasound examination in determining chorionicity in twin pregnancies. The "T sign" is really the absence of a twin-peak sign(or lambda (l) sign) and is used in ultrasound assessment of multifetal pregnancy. It refers tothe lack of chorion extending between the layers of the intewin membrane, denoting a monochorionic diamniotic pregnancy.', 'role': 'assistant'}]