Final answer:
The sentence 'Marcos es el primer gerente de su familia' is grammatically CORRECT.
Step-by-step explanation:
The sentence 'Marcos es el primer gerente de su familia' is grammatically CORRECT.
In this sentence, the subject is 'Marcos', which is performing the action of being the first manager in his family. The verb 'es' is the conjugation of the verb 'ser' (to be) in the third person singular form.
'El primer gerente de su familia' translates to 'the first manager of his family'. Here, 'primer' is an adjective that agrees in gender and number with 'gerente', and 'de su familia' means 'of his family'.
Learn more about Spanish grammar