This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Embryology and abdominal wall layer, Subject name: Anatomy
A young athlete after rigorous training and strict diet control develops 'washboard stomach'. Which of the following structure mark its lateral border ? 
Select and explain. 
A. Linea alba, B. Linea semilunaris, C. Linea semicircularis, D. Transversalis fascia
B: Linea semilunaris
Answer: B: Linea semilunaris 
Explanation: * "Washboard stomach" refers to very strong,well-definedabdominalmuscles. * Its lateral border is marked by linea semilunaris which is a curved line along the lateral border of the rectus abdominis. * Linea semicircularis (Arcuate line) defines the lower limit of the posterior layer of the rectus sheath * Linea alba is a tendinous median raphe between the two rectus abdominis muscles. * The falx inguinalis (conjoint tendon) is formed by aponeuroses of the internal oblique and transverse abdominal muscles