27. S1. After substitution in facultative obligations, the loss of the principal through the fault or negligence of the debtor shall render him liable for damages in favor of the creditor. S2. In alternative obligations, what converts the same into a pure or simple obligation is the communication of choice of prestation to be performed by the debtor.*

(A) both are true

(B) both are false

(C) only S1 is true

(D) only S2 is true

Brief explanation will do. Thanks!