A scientist, using a telescope, sees arcs of light around a galaxy. In 3–5 sentences, explain the cause of the arcs of light.

What is the function of nucleic acids

1. emigration the movement of people from one place to another 2. immigration a situation in which resources are being used up at a faster rate than they can be replenished 3. migration the leaving of one's homeland to settle in a new place 4. overpopulation the movement of people to a new country 5. sustainable development a situation in which the birth rate is not sufficient to replace the existing population 6. underpopulation the ability to meet current needs without reducing the ability to meet future needs 7. unsustainable development the increase in the population of a city 8. urbanization a situation in which the number of people exceeds the available natural resources in an area

Which of the following was not a major animal on land during the carboniferous period? amphibians insects both a and b none of the above