Auroras are lights that appear at earth’s northern and southern poles. what is the main cause of an aurora? 1.solar wind enters earth’s atmosphere, and particles interact with ions. 2.bubbles of gas are ejected from earth’s outer crust. 3.sunlight reflects off the surface of the moon during an eclipse. 4.the northern and southern poles are cooler than the rest of earth.

THE ANSWER IS A./Solar wind enters Earth’s atmosphere, and particles interact with ions.

Explanation: I DID THE TEST ;)

"1. it should be, it has been for about 20 years, and it's really not much different in the end than breeding animals to have particular traits. there are always concerns about genetically engineered animals/plants affecting the environment in unexpected negative ways, but i can't think of an example where the fears didn't turn out to be baseless.  

first, as you point out, it would be a great advance in pharmacology, to be able to tailor drugs and their doses to me. the pros involve better medical treatment. the cons involve privacy issues like insurance companies denying coverage to people with genetic risk factors. looking at dna markers wouldn't affect the frequency of genetic diseases, but it would allow detection of them earlier. and ok, actually i suppose that if people used this information to avoid having children with genetic diseases, some might decrease in frequency."

wha is what i will use to get my free points