Conjugate the verb and underline the correct option --> Aunque yo ………………………………. (saber) la verdad, no te lo/la podría contar

Aunque yo supiera la verdad, no te la podría contar.

If we analyze the second clause in the sentence, we notice that the verb poder is in the conditional tense. This implies that the 'aunque yo'  is to be translated in the typical 'if' or 'si' clause structure. This is due to the fact that 'si' clauses in Spanish tend to abide by the following general rule:

• verb in the imperfect subjunctive, followed by verb in the conditional. 

Hence saber takes the first person imperfect subjunctive, otherwise written as 'supiera'. 

Looking over the sentence once more, we notice that 'lo/la' refers to the object of the sentence, namely 'la verdad'. 'Verdad' is a femenine noun so we can safely underline 'la' as the correct option in this case.