posted by Gail .
Darwin was able to formulate his theory of evolution based on several facts. Which of the following facts was unavailable to Darwin in the mid-nineteenth century?
Natural resources are limited.
Individual organisms in a population are not alike.
Characteristics are inherited as genes on chromosomes.
Most populations are stable in size.
All populations have the potential to increase.
I was thinking that it was "Characteristics are inherited as genes on chromosomes."