Final answer:
The outbred stock of mice are mice with diverse genetic backgrounds, which are useful for experiments assessing the genetic basis of traits and observing genetic drift in natural populations.
Step-by-step explanation:
An outbred stock of mice refers to a group of mice that are bred to maintain a high level of genetic diversity. This is achieved by not allowing close relatives to breed over many generations, thus creating a population that retains a varied genetic background. Therefore, the correct answer to the question is c) Mice with diverse genetic backgrounds. Outbred mice are often used in experiments where genetic variability is important. For instance, when studying the genetic basis of population-wide traits or assessing the effects of genetic drift in a population over time, outbred stocks provide useful models because of their genetic diversity, which might be more representative of natural populations compared to inbred strains.