Final answer:
The correct direct object pronouns for the given sentences are 'Lo tienes' and 'La busca'.
Step-by-step explanation:
The correct direct object pronoun for the sentence 'Tienes el libro de español' is Lo tienes. The pronoun 'lo' represents the masculine singular object 'el libro'. Therefore, the correct answer is 'Lo tienes'.
For the sentence 'Marcos busca la llave', the correct pronoun is La busca. The pronoun 'la' represents the feminine singular object 'la llave'. So, the correct answer is 'La busca'.
Learn more about Direct object pronouns in Spanish