How does the author support his claim that there are tipping points for social problems? (In the tipping point)

How is the underlined word used in the following sentence? juan was elected president of his class. juan is underlined. a. subject b. predicate nominative c. direct object d. verb

Vvnici prece di evidence would best support teason #to the history of using animals for research extends asfar back as 322 bce, when early greek physician-scientists, such as aristotle and erasistratus,performed various experiments on living animals.0 animal research played an essential role in thedevelopment of herceptin and tamoxifen, twomedications that have already saved the lives ofthousands of women who have been diagnosed withbreast cancer.even those who believe in testing on animals when it isnecessary for vital medical research practice what isknown as "the 3 rs"-reduction, refinement, andreplacement to reduce the number of animals usedfor testingbiologists believe that chimpanzees share at least 98.4percent of the same dna as humans and gorillas shareat least 97 percent, making primates a popular andlikely choice for the testing of products intended for humans

What would happend if organ systems failed to work together