What is the evolutionary origin of light skin in humans?
a. light skin evolved several times in areas where there was no malaria.
b. light skin evolved several times in response to low ultraviolet light levels.
c. light skin evolved several times in response to high ultraviolet light levels.
d. light skin evolved as an adaptation that decreased folate levels in humans.
e. one light-skinned race evolved 100,000 years ago and spread throughout europe

[120 total points] (public health) in one of the largest human experiments ever conducted, in 1954 a randomized controlled trial was run to see whether a vaccine developed by a doctor named jonas salk was effective in preventing paralytic polio. a total of 401,974 children (ages 6–9), chosen to be representative of those who might be susceptible to the disease, were randomized to two groups: 200,745 children (the control group c) were injected with a harmless saline solution (a placebo) and the other 201,229 children (the treatment group t) were injected with salk’s vaccine.what was the point of giving saline solution to the children who didn’t get the vaccine? explain briefly.

What is a good description of wellness

In which way does nicotine cause addiction? by stimulating the brain’s pleasure center by increasing blood-sugar levels by decreasing dopamine levels by reducing depression and anxiety