(c) plants use oxygen to make their own food
we can use process of elimination here. a is not correct. animals do not make their own food. c is not correct. plants use carbon dioxide, not oxygen to power photosynthesis. d is not correct. decomposers break down dead animals. therefore, b is correct. plants are food for some consumers.
speed = (change in distance) / (time for the change)
distance from top to bottom of segment c = (6 - 0) = 6 m
time from beginning to end of segment c = (14 - 4) = 10 s
speed = (6 m) / (10 s)
speed = 6 m/s