Under what circumstances can witnesses before congress legally refuse to answer questions

In witch of these areas were the early bantu successful in part to there iron working skills ? check all that apply -agriculture -gathering -navigation -trade -warfare

Which of following most accurately describes china today?

What were the purposes of salt? check all of the boxes that apply. -to achieve peace -to protect the security of the united states -to form an alliance against communist nations - to stop the nuclear arms race - to give the united states an advantage over the soviet union