Final answer:
A plant with perfect flowers contains both female and male reproductive structures within each flower, which makes the flowers hermaphroditic or androgynous, capable of self-pollination or cross-pollination. The correct option is d.
Step-by-step explanation:
A plant with perfect flowers is one where the individual plant's flowers contain both female and male structures. The correct description of a plant with perfect flowers is an individual plant whose flowers contain both female (carpels) and male (stamens) structures. An individual plant whose flowers contain both female and male structures. These types of flowers are also known as hermaphroditic or androgynous, and the presence of both reproductive structures (androecium for males and gynoecium for females) allows such flowers to potentially self-pollinate or be cross-pollinated.