The river that many other rivers connect to in north america

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.

The layers of earth are based on what two sets of characteristics?

The covers all of earth like a thin shell, but it is not a solid sheet of material. it is broken up into several large sections and many smaller ones. fill in the blank.