In which pair of events did the first event most directly influence the second?
a. discovery of gold in california — louisiana purchase
b. building of the transcontinental railroad — disappearance of the frontier
c. settling of the oregon territory — passage of the homestead act
d. assimilation of native american indians into american society — passage of the dawes act

Two technicians are discussing oil changes. technician a says that waste oil and old filters need to be disposed of according to the law. technician b says that old filters can be returned to the parts department for a core value. which technician is correct?           a. technician a only   b. both technicians a and b   c. technician b only   d. neither technician a nor b