What abitotic factor was used to classify regions into plant hardiness zones?

i believe it is "they are not used up by reactions" as the answer to your question, text me back if this is correct because i just learned this.

in the year 2850, humans successfully colonized mars. the martian modules that were constructed could hold only a small population of people. it is now a century later, and the population on mars has grown to 600 people. of the current mars population, 45 people express the recessive phenotype for phenylketon- uria (pku) syndrome (pp genotype).

explanation: