What is the role of collagen in the body?

a) it slows down reactions
b) it speeds up reactions
c) it transports oxygen
d) it provides structural support

in cartography, a contour line (often just called a "contour") joins points of equal elevation (height) above a given level, such as mean sea level. a contour map is a map illustrated with contour lines, for example a topographic map, which thus shows valleys and hills, and the steepness or gentleness of slopes.

explanation:

1. they vary with a higher number because boiling is way hotter than melting