In which sentence is the underlined word or group of words a predicate nominative? Polio is a contagious disease that has mostly been eradicated. Jonas Edward Salk became famous for developing a polio vaccine. In the 1940s, polio was widespread.

The correct answer should be "a contagious disease" if that is underlined. That is because it has the "is" which is a copulative verb and it has "a contagious disease" which is a predicate nominative that builds a full predicate with the copulative verb