Angiosperms

The correct option is (C): Embryo sac.

Let's evaluate both statements: Assertion (A): The statement that a typical unfertilized, angiosperm embryo sac is 8-nucleate and 7-celled is correct. The embryo sac typically has 8 nuclei, with 7 cells, including the egg cell and the two synergids, along with other cells like the central cell containing two polar nuclei. Reason (R): The statement that the egg apparatus has 2 polar nuclei is true, but it is unrelated to the structure described in the Assertion. The egg apparatus consists of the egg cell and two synergids, while the polar nuclei are part of the central cell in the embryo sac. Thus, both statements are true, but Reason (R) does not correctly explain Assertion (A).