Is it necessary to come to a complete stop at a stop sign, even if the intersection is clear? a. if you don’t see any approaching cars, there is no need to come to a complete stop b. whenever you see a stop sign, you must come to a complete stop behind the stop line, crosswalk, or at the corner c. only stop if you see pedestrians crossing d. stop means slow down. no one expects you to actually stop

Which of the following best reflects what we know about how the flu virus moves between species? a) the flu virus in a pig is mutated and replicated in alternate arrangements so that humans who eat the pig products can be infected. b) a flu virus from a human epidemic or pandemic infects birds; the birds replicate the virus differently and then pass it back to humans. c) an influenza virus gains new sequences of dna from another virus, such as a herpesvirus; this enables it to be transmitted to a human host. d) an animal such as a pig is infected with more than one virus, genetic recombination occurs, the new virus mutates, the virus is passed to a new species such as a bird, and the virus mutates again and can now be transmitted to humans.