Final answer:
The correct answer to the question is 'O comienza; comienzo'.
Step-by-step explanation:
The correct answer to the question is 'O comienza; comienzo'. In the given sentence, 'Hoy, Carlota (O comienza; comienzo) su clase a las nueve de la mañana y yo a las once', the subject 'Carlota' is conjugated with the verb 'comienza' and the subject 'yo' is conjugated with the verb 'comienzo'. The verb 'comienza' is used for the third person singular form and 'comienzo' is used for the first person singular form.
Learn more about Conjugation of Spanish verbs