Final answer:
The indirect evidence that DNA is the genetic material in eukaryotes is the correlation between ploidy and the amount of DNA, with diploid cells having twice as much DNA as haploid cells. Option number C is correct.
Step-by-step explanation:
The indirect evidence that DNA is the genetic material in eukaryotes is the correlation between the ploidy of the cell and the amount of DNA. The correct answer to the question is C) Ploidy; DNA.
This correlation is observed because diploid cells (2n), which contain two complete sets of chromosomes, have twice as much DNA as haploid cells (n), which contain only one set of chromosomes. In humans and other eukaryotes, somatic cells are typically diploid, while gametes, or sex cells like sperm and eggs, are haploid.