certain breeds of pets have weaknesses and live shorter lives because of\ninbreeding.\nreproduction.\ngenetic…

Brief Explanations:

Inbreeding increases the likelihood of inheriting harmful recessive genes, leading to weaknesses and shorter - lived pets. Reproduction is a general process and not the specific cause here. Genetic diversity is beneficial and reduces such problems. Natural selection is about survival of the fittest in nature and not the cause of these pet - related issues.

Answer:

inbreeding.