a reasonable theory
reasonable
/ˈrēz-nə-bəl/
adjective
being in accordance with reason
not extreme or excessive
moderate, fair
reasonable requests
noun
a copy that is not exact but is fairly close —sometimes used in a joking way
The house is a reasonable facsimile of his original home.
idiom
without question : definitely
The test results proved beyond (all/any) doubt that he was not the child's father.