29. Reverse genetics approaches involve (A) Systematically inhibiting the functions of one or many genes (or gene products), and measuring the phenotypic consequences correctly. (B) Measuring a phenotype of interest (such as cell growth), applying an intervention (such as radiation exposure) to generate a large collection of mutants, and identifying changes to the phenotype of interest. (C) Treating an organism with a chemical mutagen or other agent to induce mutations, observing a phenotype of interest, and mapping the gene(s) responsible for the phenotype. (D) all of the above.