Identifying Continuous (Range of Traits) and Discontinuous (Distinct Categories) Variation in Order Steps: - Continuous variation involves traits influenced by multiple genes and environment, showing a smooth range of phenotypes without clear categories, such as human height. - Discontinuous variation involves traits controlled by one or few genes, resulting in distinct categories with no intermediates, such as blood groups (A, B, AB, O). - Evaluate each option to find the row listing continuous variation first, followed by discontinuous variation. - Option A matches: height (continuous, gradual spectrum), blood group (discontinuous, fixed types). Why A is correct: - Height demonstrates continuous variation through polygenic inheritance and environmental factors, producing a bell-curve distribution; blood group exemplifies discontinuous variation via alleles at a single locus yielding discrete phenotypes. Why the others are wrong: - B: Blood group and hair colour both show discontinuous variation with distinct categories (e.g., A/B/AB/O and black/brown/blonde/red). - C: Hair colour (discontinuous, categorical types) followed by body mass (continuous, range of values) reverses the required order. - D: Blood group (discontinuous) followed by height (continuous) reverses the required order. …