Right answer: Te pusiste
This is an example of the usage of the reflexive pronouns.
Reflexive pronouns are personal pronouns that complement reflexive verbs, and agree in person and number with the subject of the sentence.
It is important to note that Reflexive Pronouns always refer to the subject, indicating that the action that the subject performs falls on it at the same time.
Now, Reflexive pronouns are located:
1. Before a verb in any of its personal forms.
2. Before the imperative in negative form and following the affirmative imperative.
3. Before a verbal periphrasis or behind the infinitive of it.
4. In the formula to be + gerund, the pronoun can also go before or after.
And according to the subject are:
1st person singular: Yo (I) me
2nd person singular: Tú (You) te
3rd person singular: Él/Ella/eso/esa (He, She, It) se
1st person plural: Nosotros (we) nos
2nd person plural: Ustedes (You) (In latinAmerica) se / Vosotros (In Spain) os
3rd person plural: Ellos/Ellas (They) se
It should be noted that these reflexive pronouns are used to change the meaning of the verb, accentuate the action or indicate that the action directly affects the subject.
In this same context, the sentence we have has the subject Tú (you) wich is the 2nd person singular, and we are talking about the first case: Reflexive pronun placed before a verb.
Hence the reflexive pronoun to use is:
te
Hence, the complete sentence is:
Tú te pusiste muy nerviosa cuando te tocó bailar
You were very nervous when you had to dance
Where te is written before the verb pusiste.
The options se puso (3rd person singular) and me puse (1st person singular) are incorrect because are not according the subject of the sentence.