Tú tienes una directora inteligente, bonita y alta.
Explanation:
Tú tienes una directora inteligente, bonita y alta. This means: You have an intelligent, pretty and tall director. The indefinite articles in Spanish are: un, unos, una, unas. <u>Uno </u>y <u>unos</u> are both <u>masculine</u>, uno is singular and unos is plural. <u>Una</u> y <u>unas</u> are<u> feminine</u>. Una is singular and unas is plural. The sentence refers to "a directora" which is a female director. So the only possible indefinite article is una.