Under the collision theory, the particles must collide with and
for a reaction to occur.
a surface area; correct orientation
b sufficient energy, correct orientation
c catalyst; sufficient energy
d rate; sufficient energy

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:

the answer is c

tell me if wrong