Answer:
Here we need to conjugate the verb "decir" with the person "tú"
The most commonly used conjugations are:
1) Tú dices la verdad (present)
2) Tú diras la verdad (future)
3) Tu decias la verdad (Imperfect tense)
4) Tu dijiste la verdad (perfect tense)
There are a lot of other possible conjugation, but the listed are the most used ones.
