The given blank can be filled with selecting.
It has been shown by Belyaev and Trut that foxes can be domesticated, over the time of various generations, by selecting and mating animals with certain traits, like responses to feeding, handling, and others.
A sustained multi-generational association in which one group of species presumes a substantial extent of effect over the care and reproduction of another group to secure a more predictable supply of resources from that latter group is known as domestication.
Death by hypoxia can be caused by airway obstruction(strangulation) or poison(cyanide, CO).
In the case, there is a toxicology report saying the victim is poisoned by cyanide. The organ damaged also diffuse and not concentrated. Cyanide works by inhibiting an enzyme in the mitochondria that use oxygen. Therefore, the cells can't oxygen for cellular respiration, cause the tissue die of hypoxia. The oxygen is there but it can't be used. The laboratory report that found high oxygen level in the blood also supports the cyanide poisoning.
I believe it's feeding relationships between different organisms
Dendrochronology, or tree-ring dating, provides absolute dates in two different ways: directly, and by calibrating radiocarbon results. Cross-dating determines the age of undated wood by directly matching ring patterns with trees of known age.
Hope this helps ^^
