The best and most correct answer among the choices provided by the question is the third choice "natural monopolies"
Natural monopolies<span> arise where the largest supplier in an industry, often the first supplier in a market, has an overwhelming cost advantage over other actual or potential competitors; this tends to be the case in industries where fixed costs predominate.</span>
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<span>C) seeing US astronauts planting the US flag on the moon symbolized a US victory It practically restored public confidence in the USA about their place in the space race and international politics. </span>