what kinds of investigations might have led to our current understanding of matter and energy? why is it important for scientists to use the same scientific method and consistent measurement units?

a. a primary source combines several different accounts of an event. b. a primary source generally benefits from having been written after an event.

explanation:

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.