Final answer:
The correct Spanish conjugation of the verb 'to have a birthday' is 'cumplo años'.
Step-by-step explanation:
The correct Spanish conjugation of the verb 'to have a birthday' is 'cumplo años'. This is the first person singular form of the verb and it translates to 'I have a birthday'. Here, 'cumplo' is the conjugated form of the verb 'cumplir' which means 'to have/celebrate'. So, the correct sentence would be 'Mi amiga Rosa cumplo años mañana.'
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