Presenting part most commonly encountered in longitudinal lie is -

Ans. is 'b' i.e., Vertex o The presenting part is defined as the part of the presentation which overlies the internal os and is felt by the examining finger through the cervical opening.o Thus, in cephalic presentation, the presenting part may be vertex (most common), brow or face, depending upon the degree of flexion of the head.o Similarly, the fetal legs in a breech presentation may be flexed (complete breech), extended (frank breech) or a foot may be present (footling).Preponderance of Lie, presentation and presenting partLiePersentationPresenting Part of CephalicLongitudinal (99.5%)Cephalic (96[?]5%)Vertex-(96%)Transverse Oblique UnstableBreech (3%), Shoulder (0.5%)Brow face (0[?]5%)