I thought her explanation was perfectly/entirely/completely 'plausible'. [=I believed her explanation]
a 'plausible' [='possible'] conclusion
a 'plausible' excuse
(..) and the Independent Counsel's investigation had requested them. Because high-level political officials scrambled to limit the investigation... and establish plausible deniability... for the upper echelons of the network, including Bush himself. So who is this guy, and how did he come to power? (..)2009 Loose Change 9/11: An American Coup