The correct option is
A Mass of epithelial cells in the Graafian follicles
Cumulus oophorus is a cluster of cells (called as cumulus cells
), that surround the oocyte both in the Graafian follicle and after ovulation.
In the antrial follicle, it may be regarded as an extension of the membrane granulosa. Functions of the cumulus oophorus include coordination of follicular development and oocyte maturation.
Hence, the correct answer is option B.