Please guys do this please

Which environmental change allowed people to travel by land between asia and north america a.human apaption to arctic environments b.the introduction to horses to north america c.the formation of ice sheets on land d.a rise in ocean temperatures

Which of the following makes someone an entrepreneur? a.) becoming a partner in a major law firm b.) becoming a highly paid dancer c.) earning a lot of money as a computer programmer d.) running a company that hires people to fix computers

Which of the following  bestillustrates a negative reinforcer?               a.  copland gives up candy to stave off chronic acid indigestion.    b.  nancy learns that she prefers chocolate over vanilla.    c.  carmine changes his major to english lit after failing a math exam.    d.  on a hot day, lindberg always drinks lemonade.