Final answer:
The correct verb conjugation for the sentence is 'cantas'.
Step-by-step explanation:
The correct verb conjugation for the sentence "¿Con cuánta frecuencia cantas?" in the 'tu' form is cantas. This is the second person singular form of the verb 'cantar' which means 'to sing' in English.
Learn more about Verb conjugation in the 'tu' form of the verb 'cantar' in Spanish