1. what subject pronoun would you use when talking about my grandmother?
a. ellas
b. yo
c. ella
d. vosotras

2. what subject pronoun would you use when talking about marcos?
a. ellas
b. ellos
c.él
d. ustedes

4. what subject pronoun would you use when talking to your parents?
a. tú
b. ellos
c. usted
d. ustedes

5.what subject pronoun would you use when talking about maría y ana?
a. ellas
b ella
c. vosotras
d. nosotras

A pronoun replaces a noun in order to avoid repetition. In this way, subject pronouns function as the subject of a verb. These are the following subject pronouns in Spanish:

FIRST PERSON.

Singular: yo (I)

Plural: nosotros/nosotras (we)

SECOND PERSON.

Singular: Tú/usted

Plural: Ustedes/vosotros/vosotras

THIRD PERSON:

Singular: él/ella

Plural: ellos/ellas

So, solving this problem, we have:

1. The correct answer is:

c. ella (she). Pronombre Tercera Persona del Singular (Femenino)

2. The correct answer is: 

c. él (he). Pronombre Tercera Persona del Singular (Masculino)

4. The correct answer is: 

d. ustedes (you). Pronombre Segunda Persona del Plural.

5. The correct answer is: 

a. ellas (they). Pronombre Tercera Persona del Plural (Femenino)

Nota. Ellos - Es válido tanto para el género masculino como para referirse a mujeres y hombres en conjunto. En 4. se usa el segundo caso.

1. The correct answer is C. ella.

The pronoun ella means she in Spanish. Given that you are talking about one of you grandmas, the pronoun has to be singular (so, ella instead of ellas), and given that your grandmother is a woman, you need a female pronoun, ella. Yo means I, and vosotras means you (but plural).

2. The correct answer is C. él.

The pronoun él means he in Spanish. Given that you are talking about one person only, the pronoun has to be singular (so, él instead of ellos). Also, given that Marcos is a man, you need to use the male pronoun él. Ustedes means they (plural, and polite form).

4. The correct answer is D. ustedes.

The pronoun ustedes means they in Spanish, however, it is not a regular you - it is the polite version of the plural noun ellos/ellas. Since we are talking about someone's parents here, you want to address them a bit more formally than your friends, and that's why you say ustedes. Ellos could be the correct answer if both of your parents are men; if not, ustedes should be used.

5. The correct answer is A. ellas.

The pronoun ellas means they in Spanish. Given that you are talking about more than one person, you need to use the plural pronoun, which is ellas (insted of ella). Also, given that both individuals are girls, you need to use the female pronoun ella. Vosotras means you (plural), and nosotras means we (plural).