In a family with two brothers, one brother's thumbs are straight while the
other's thumbs are bent. the most likely reason for this difference is that the
brothers:

it should be d) transitional fossils.

they show the gradualism of evolution throughout a period of time

the statements that apply here about binary star system are

"have stars that might appear to wobble"

"often have one star that is brighter than other"

a binary star is a star system consisting of two stars revolving around their common barycenter. systems of two or more stars are called multiple star systems.

answerblank(1); ecological; blank(2); evolutionary;