I thought her explanation was perfectly/entirely/completely 'plausible'. [=I believed her explanation]
a 'plausible' [='possible'] conclusion
a 'plausible' excuse
(..) that we have got to address is what the hell is it? About % of the population aren't affected immediately. It is viral. it has to be viral. There is no plausible alternative. And like any virus, once we find its origin, we can develop a vaccine. - We find it, contain it.. - That's Dr. Fassbach. (..)2013 World War Z