A bite from the tsetse fly invariably paralyzes its victims unless an antidote ... ...

Determine whether or not there is an error in the underlined portion of the sentence above. If there is no error, select answer choice "A".
(A) its victims unless an antidote is administered
(B) ...
(C) ...
(D) ...
(E) ...

*This question is included in Nova Press: Set A - Pronoun Errors