The ovule of an angiosperm is technically equivalent to: Megaspore, Megaspore mother cell, Megasporangium, Megasporophyll

The archesporial cells (2n) of young ovule cut off the parietal cell and are differentiated into megaspore mother cells (2n). The diploid megaspore mother cells then undergo meiosis to form a linear tetrad of megaspores. Megaspore is the first cell of the female gametophyte. Out of four, the functional megaspore undergoes megagametogenesis to 8-nucleate and 7-celled embryo sac. Ovule serves as megasporangium wherein megaspores production occurs.Therefore, the correct answer is option C.