<h3><em><u>BLANK </u></em>mujeres inteligentes y bonitas. Unos or Unas?</h3>
<em>Answer : </em><u><em>Unas</em></u> mujeres inteligentes y bonitas.
<em>Explanation : The subject in this sentence is "mujeres", that is a feminine plural noun, so the article must be feminine plural too. </em><u><em>Unas</em></u><em>.</em>