[Solved] What is the greatest benefit of using a testcross to determine an unknown genotype? A) The homozygous recessive parent is obvious to the naked eye. B) The homozygous parent is the only one whose crossovers make a difference. C) A progeny's phenotype reflects the contribution from the heterozygous parent. D) All of the progeny will be heterozygous. Atoms: The basic units of matter composed of a nucleus surrounded by electrons, representing the smallest component of an element that retains its chemical properties. Compound: A substance formed by the chemical combination of two or more elements in fixed proportions. Atomic Symbol: A notation of one or two letters representing a chemical element (e.g., H for hydrogen, O for oxygen) used in chemical equations and formulas. Atomic Symbols: Abbreviations or short notations used to represent chemical elements (e.g., H for hydrogen, O for oxygen).