Assume that a cross is made between tall and dwarf Alsatian red-ribbed spider plants. The F1 generation showed intermediate height, while the F2 generation showed a distribution of height ranging from tall to dwarf, like the original parents, with many heights between the extremes. These data are consistent with the following mode of inheritance: A. artificial selection B. codominance C. multifactorial inheritance D. incomplete penetrance E. alternation of generations F. hemizygosity Solution D. Incomplete penetrance. Penetrance is the frequency with which individuals of a guven genotype manifest at least some degree of specific mutant phenotype associated with a triat.In incomplete or reduced penetrance, some individuals will not express the trait even though they carry the allele..