"The two assumptions in competition are like islands in a sea of
                    chaos, as different as life and death, matter and the void. One
                    cannot learn which is correct by pure logic; the answer will
                    eventually be reached through an accumulation of objective
                    evidence. Moral reasoning, I believe, is at every level
                    intrinsically 
consilient with -- compatible with, intertwined with
                    -- the natural sciences. (I use a form of the word "
consilience"
                    -- literally a "jumping together" of knowledge as a result of the
                    linking of facts and fact-based theory across disciplines to
                    create a common groundwork of explanation -- because its
                    rarity has preserved its precision.) "
http://www.theatlantic.com/issues/98apr/biomoral.htmTutorial Answer 8 
                (b) is correct because, by Whewell's definition, 
consilience refers to the gathering of
                different forms of evidence (observation or experiment, from two or more separate
                fields) that all converge, or can be grouped under, a single explanatory model. (a) is
                not correct because it is too vague to say anything specific about consilience. (c) is
                not untrue per se, but it does not distinguish consilience from many other forms of
                reasoning such as deduction. And of course (d) cannot be correct if one or more of
                the other answers is not correct.