Final answer:
The missing word in the sentence 'Tatiana tiene un ______ que se llama Valentin' is 'primo' which means cousin in Spanish.
Step-by-step explanation:
For the given sentence, 'Tatiana tiene un ______ que se llama Valentin,' the missing word should be 'primo.' The word 'primo' means cousin in Spanish. In this case, Tatiana has a cousin named Valentin.
Learn more about Spanish word for cousin