I recommend that you check in your suitcase early.
The correct form of the verb "facturar" in this sentence is "factures," which corresponds to the second-person singular form of the verb in the present subjunctive tense. Therefore, the correct option is:
b. factures
In this sentence, "Recomiendo que tú..." (I recommend that you...), the verb that follows "que tú" needs to be conjugated in the present subjunctive form. "Factures" is the appropriate form of the verb in this context, indicating a recommendation or suggestion for the action of checking in the suitcase early.
