Engaging diameter of well flexed head in vertex presentation is -
High-Yield Explanation
Ans. is 'a' i.e., Suboccipito - bregmatic DiametersMeasurement in cmAttitude of the headPresentationSuboccipito - bregmatic9[?]5 cmComplete flexionVertexSuboccipito - frontal10 cmIncomplete flexionVertexOccipito - frontal11[?]5 cmMarked deflexionVertexMento - vertical14 cmPartial extensionBrowSubmento - vertical11[?]5 cmIncomplete extensionFaceSubmento - bregmatic9[?]5 cmComplete extensionFace