Distinguishing population variation graphs Steps:

• Population variation data typically appears as frequency distributions (e.g., histograms, bell curves) showing trait spread.
• Graph A: Histogram of trait frequencies, indicating normal distribution in population.
• Graph B: Bell curve plotting trait values vs. occurrence, common for quantitative traits.
• Graph D: Bar graph of allele frequencies, reflecting genetic variation.
• Graph C: Lacks frequency-based trait variation, instead showing unrelated trend (e.g., time series).

Why C is correct:

• C represents a phylogenetic tree or lineage diagram, which illustrates evolutionary relationships across species, not variation within a single population (per cladistics definition).

Why the others are wrong:

• A shows quantitative trait distribution, standard for population variation studies.
• B depicts normal distribution of a characteristic, directly from population data.
• D illustrates categorical variation (e.g., blood types), typical of population genetics.

Final answer: C