Final answer:
The appropriate verb in the future tense is 'dirá' (Option B).
Step-by-step explanation:
In this sentence, the appropriate verb in the future tense should be dirá (Option B). The sentence is talking about an action that will happen in the future, so we need to use the future tense. The correct conjugation for the verb 'decir' (to say) in the third person singular form is 'dirá'. Therefore, the correct sentence would be 'Hoy, María le dirá la verdad a su madre.'
Learn more about Verb conjugation in Spanish