This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Miscellaneous, Subject name: Radiology
Lambda sign on ultrasound is seen in? 
Select and explain. 
A. Ectopic pregnancy, B. Twin pregnancy, C. Hyaditiform mole, D. Fibroid
B: Twin pregnancy
Answer: B: Twin pregnancy 
Explanation: Ans BTwin peak sign (also known as the lambda (l) sign) is a triangular appearance of the chorion insinuating between the layers of the intertwin membrane and strongly suggests a dichorionic twin pregnancy.