Choose the sentence that has the correct form of verb ser. el ingeniero son inteligente. ana es diseñadora. el programador ser mexicano. ella eres alta.

The spanish verb ser (To be) is conjugated in present tense as follows:

1st person singular Yo (I): soy

2nd person singular (informal) Tú (You): eres  

2nd person singular (formal) Usted (You): es  

3rd person singular Él/Ella/eso/esa (He/She/It): es  

1st person plural Nosotros (We): somos  

2nd person plural Ustedes (You) (In latinAmerica): son  

2nd person plural Vosotros (You) (In Spain): sois

3rd person plural Ellos/Ellas (They): son

Hence, the correct sentence is:

(Ana is a designer)

Ana is substituted by the personal pronoun ella (she), and according to the conjugation listed above, the correct form of the verb ser in present tense for this pronoun is es.

The other sentences are incorrect because:

-El ingeniero son inteligente

El ingeniero is substituted by él (he) and the right conjugation is es

El ingeniero es inteligente (The engineer is smart)

-El programador ser mexicano.  

El programador is substituted by él (he) and the right conjugation is es

El programador es mexicano (The programmer is Mexican)

-Ella eres alta.

The right conjugation for ella (she) is es

Ella es alta (She is tall)