challenge: What were some of the organizations led by Meir Ya'ari?
  
  A. Hashomer Hatzair, Kibbutz Dati, and Mapai
  B. Hashomer Hatzair, the Israeli Labor Party, and the Knesset
  C. Hashomer Hatzair, Kibbutz Artzi, and Mapam
  D. Kibbutz Artzi, Mapam, and the Israeli Labor Party
  Answer: 