<prompt> Diameter of graafian follicle at the time of ovulation is -10mm15mm20mm25mm  <response>: Ans. C. 20mmOvulation is aprocessby which a secondary oocyte is released from the ovaryfollowingrupture of a mature Graafian follicle and becomes available for conception.There is a pre - ovulatory enlargement in the Graafian follicle and it measures about 20 mm at the time of ovulation. 