Final answer:
The mature female gametophyte in angiosperms consists of seven cells, which include one egg cell, two synergids, three antipodal cells, and a large central cell with two polar nuclei. The correct answer is d. 7.
Step-by-step explanation:
In angiosperms, the mature female gametophyte is a structure involved in sexual reproduction. It is formed within the ovule inside the female reproductive organs of the flower. When a megasporocyte undergoes meiosis in the ovules, it produces four haploid megaspores. Among these, one is selected to become the female gametophyte, commonly known as the embryo sac. This selected megaspore undergoes three rounds of mitosis to produce eight nuclei, which are organized into seven cells. These cells include one egg cell, two synergids at the micropylar end, three antipodal cells at the opposite end, and a large central cell containing two polar nuclei that will fuse to form a diploid nucleus. Therefore, the mature female gametophyte of an angiosperm consists of seven cells. The correct answer to the student's question is d. 7.