. It has been observed that organisms on islands are different from, but closely related to, similar forms found on the nearest continent. This is taken as evidence thatA) island forms and mainland forms descended from common ancestors. B) common environments are inhabited by the same organisms. C) the islands were originally part of the continent. D) the island forms and mainland forms are converging

       The right answer to this question is option A) island forms and mainland forms descended from common ancestors.

       It's known in science that a long time ago, all the continents were only one, united all together in a bigger one. This can be observed by the way every continent can fit another one.

       A proof of that too, is evolution, when we find organisms in an island that share some characteristics with organisms from another island, that can mean some things, they come from the same place, or these islands share characteristics that lead these organisms to be this way through evolution.