What are some primary contributors to background radiation?

cars, jets, and trains

televisions and computers

fossil fuels and oxygen

plants, animals, and cosmic rays

List two limitations of natural selection

Select three sports that require participants to be highly fit before the beginning a: snowboarding b: skydiving c: rock climbing d: bungee jumping e: free diving f: hiking

Give two examples of what would occur if one of the pairs did not match or had an extra chromosomes. explain how this might occur, and if it would be dangerous to the individual. fast.