Please answer the following question: Given the following passage  "Debate remained limited, and major decisions regarding the economy and defence were avoided or dealt with cursorily; the GPC largely remained "a rubber stamp" for Gaddafi's policies. On rare occasions, the GPC opposed Gaddafi's suggestions, sometimes successfully; notably, when Gaddafi called on primary schools to be abolished, believing that home schooling was healthier for children, the GPC rejected the idea. In other instances, Gaddafi pushed through laws without the GPC's support, such as when he desired to allow women into the armed forces. Gaddafi proclaimed that the People's Congresses provided for Libya's every political need, rendering other political organizations unnecessary; all non-authorized groups, including political parties, professional associations, independent trade unions and women's groups, were banned.",  answer the following question. Note that the answer is present within the text.  Question: Blue, red, and yellow are considered in the field of art to be what kind of colors when combined in various amounts to produce other colors?
A:
primary