What has science discovered about sub-concussive (below full concussions) blows to the head?

Which of the following statements is not true about regions? a.) regions have fixed boundaries that are determined by the region's inhabitants.b.) a region can be defined by physical characteristics, such as climate, landform, and vegetation.c.) regions can change over time.d.) a region can be defined by human characteristics, such as language, government, and economic activity.e.) the same location can be considered part of multiple regions.

Explain the popular saying "we are made of stardust. how are we made of stardust? use scientific vocab.

Drivers must always yield to emergency vehicles traveling