<prompt> THE MAIN DISTINCTIVE SIGN IN CORPUS CALLOSUM DEGENERATION ON USG IS?Tear drop signlemon signBanana signRing sign  <response>: With complete agenesis of the corpus callosum, a normal cavum septum pellucidum cannot be visualized sonographically, and the frontal horns are displaced laterally. There is mild enlargement of the Atria posteriorly--such that the ventricle has a characteristic Teardrop appearance 