Depending on the intensity and duration of activity, amino acids may contribute no more than what percentage of the energy needed

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:

there are two significant figures.

a is the correct answer