Question 20 Review Which event is the best example of erosion? 1. breaking apart of shale as a result of water freezing in a crack
2. dissolving of rock particles on a limestone gravestone by acid flin They 3. the deepening of a stream bed by pebbles rolling along the bottom of the stream
4. crumbling of bedrock in one area to form soil​

Embryonic stem cells are cells derived from an embryo. these cells can be used to create new tissues for patients suffering from certain illnesses and disorders. which statement best summarizes why the use of embryonic stem cells could be seen as unethical? a. some people consider embryos to possess rights equal to those of fully developed human beings. b. extracting stem cells from embryos is a very energy-intensive process, which consumes resources that could be used elsewhere. c. embryos are difficult to obtain, so the monetary cost of using them for research outweighs their benefit. d. the process of extracting stem cells from embryos generates biohazardous waste that cannot be safely disposed of.