Q. Obstetric conjugate measured between……

(a) Midpoint of sacral promontory to the upper inner border of the symphysis pubis
(b) Midpoint of sacral promontory to the lower margin of the symphysis pubis
(c) Midpoint of sacral promontory to the lower inner margin of the symphysis pubis
(d) Sacroiliac joint to opposite iliopubic eminence