Final answer:
The correct preterite form of the verb 'decir' for 'tú' is 'dices'.
Step-by-step explanation:
The correct answer is B. dices in the preterite form. In the dialogue, the question is asking 'What do you say?' which is addressed to 'tú' (you). In Spanish, the preterite form of the verb 'decir' (to say) for 'tú' is 'dices'.
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