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
Lambda sign or twin peak sign is seen in 
Select and explain. 
A. Diamniotic Monochorionic, B. Dichorionic Diamniotic, C. Monochorionic monoamniotic, D. None of the above
B: Dichorionic Diamniotic
Answer: B: Dichorionic Diamniotic 
Explanation: 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.