"Lemon sign" & "Banana sign" are see in-

Ans. is 'b' i.e. Spina bifida * Lemon and banana signs are ultrasonographic findings in a patient of neural tube defects (esp spina bifida).* The banana sign seen on axial imaging through the posterior fossa of fetus. It describes the way the cerebellum is wrapped tightly around the brain stem as a result of spinal cord tethering and downward migration of posterior fossa content. The cisterna magna gets obliterated and the shape of the cerebellum has the appearance of a banana. The sign persists into the second and third trimesters.