Triploid cells are formed during the process of double fertilization, which occurs in flowering plants. In this process, one sperm fertilizes the egg, while another combines with two polar nuclei to form triploid endosperm. Understanding this mechanism is essential for grasping plant reproduction and seed development. ;
A triploid cell is formed during double fertilization in flowering plants, where one sperm fertilizes the egg and another combines with polar nuclei to form triploid endosperm. This process is essential for seed nourishment and development. Thus, the correct answer is A. Double fertilization.
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