<u>Answer:</u>
The spanish verb <em>ser</em> (To be) is conjugated in <u>present tense</u> as follows:
1st person singular Yo (I): <u><em>soy </em></u>
2nd person singular (informal) Tú (You): <u><em>eres</em></u>
2nd person singular (formal) Usted (You): <u><em>es</em></u>
3rd person singular Él/Ella/eso/esa (He/She/It): <u><em>es</em></u>
1st person plural Nosotros (We): <u><em>somos</em></u>
2nd person plural Ustedes (You) (In latinAmerica): <u><em>son</em></u>
2nd person plural Vosotros (You) (In Spain): <em><u>sois</u></em>
3rd person plural Ellos/Ellas (They): <em><u>son</u></em>
Hence, the correct sentence is:
<h2>
Ana es diseñadora. </h2>
(Ana is a designer)
Ana is substituted by the p<u>ersonal pronoun</u><em> </em><em>ella</em> (she), and according to the conjugation listed above, the correct form of the verb <em>ser</em> in <u>present tense</u> for this pronoun is <u><em>es</em></u>.
The other sentences are incorrect because:
-El ingeniero <u>son</u> inteligente
El ingeniero is substituted by<em> </em><em>él</em> (he) and the right conjugation is <em>es</em>
<em>El ingeniero </em><u><em>es</em></u><em> inteligente</em> (The engineer is smart)
-El programador<u> ser</u> mexicano.
El programador is substituted by<em> </em><em>él</em> (he) and the right conjugation is <em>es</em>
<em>El programador</em><em><u> es </u></em><em>mexicano</em> (The programmer is Mexican)
-Ella eres alta.
The right conjugation for <em>ella</em> (she) is <em>es</em>
<em>Ella </em><em><u>es</u></em><em> alta</em> (She is tall)
