He silurian period occurred         

Which statement is a proper biconditional statement for the conditional statement: if a line intersects a line segment at its midpoint, then it is a segment bisector. if a line is a segment bisector, then it intersects the line segment at its midpoint. if a line does not intersect a line segment at its midpoint, then it is not a segment bisector. a line intersects a line segment at its midpoint if, and only if, it is a segment bisector. if a line is not a segment bisector, then it does not intersect the line segment at its midpoint.

Which of the following is an example of an outdated theory based on the consensus of the scientific community ? a. big bangb. geocentric solar systemc. heliocentric theoryd. plate tectonics answer : geocentric solar system

All of the following occurred due to the invention of the railroad except