In the following question, a sentence given with a blank is to be filled in with an appropriate word. Select the correct alternative out of the four.
He succeeded in proving his point with _________ logic.

* irrefutable: impossible to deny or disprove. If someone succeeds completely in proving their point, their logic must be indisputable or irrefutable.
diabolical means disgracefully bad or characteristic of a devil.

rational and analytical are fitting qualities for logic, but "irrefutable" provides the precise context for proving a point definitively.