Which factors were determined to directly cause the loss of skin pigmentation in humans as a result of natural selection? (1 point)

1. a change in the diet of human populations as they settled in colder climates

2. the clothing worn by humans in the early 8th century

3.the interaction of human populations with predators in colder climates

4.the impact of UV radiation on folate and Vitamin D levels in human populations

Clara wrote the following hypothesis for an experiment about acidophilic bacteria. bacteria cells will stop dividing in a basic (alkaline) environment because of the high ph. which statement is the best way to restate the hypothesis so that it is more specific? growing acidophilic bacteria in some environments will cause the cells to stop dividing because of ph. if the ph of their environment is changed, acidophilic bacterial cell division will be affected. if the environment of acidophilic bacterial cells becomes alkaline, the bacteria will stop dividing. the more alkaline an environment, the less cell division will occur in bacteria.