All but one of the factors listed is a major contributor to world population increases. that factor is a) increased birth rate b) decreased death rate c) increase immigration to foreign countries d) an increase in the quality of medical care

D) Increase the quality of medical care.

The major cause of population explosion or increases is due to increased birth rate and decreased death rate. Due to rapid development of science and technology, the medicinal field has improved its quality in all aspects.

During past periods, birth rate was decreased due to premature delivery, fetus born death, death during pregnancy, etc. But now due to increase in the quality of medical care, these entire problems have been rectified and the birth rate has increased which has paved way for population increase.

every el niño cycle is different. every year.

"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."