In an angiosperm, the cells with \(n\), \(2n\), and \(3n\) ploidy levels are:
\(n\) (haploid): Antipodals, synergids, and egg cells.
\(2n\) (diploid): Zygote, formed by the fusion of one sperm cell with the egg.
\(3n\) (triploid): Endosperm, formed by the fusion of the second sperm cell with two polar nuclei in the embryo sac.