The principle of competitive exclusion is best illustrated by which of the following examples?
a. a poisonous salamander is bright yellow and black in color.
b. two species of macaws (large tropical birds, like parrots) found in different locations feed on the same fruit. when these two species are found living in the same geographic region, they feed on two different species of fruit.
c. two species of ant, one large and one small, feed on plant seeds that have a special "pouch" containing a sweet substance that attracts the ants. the ants carry the seeds back to their nests, consuming the sweet substance but leaving the seed intact. seeds of a variety of sizes are used by two ant species. semibalanus and chthamalus barnacles use different spatial locations in the intertidal.
d. two species of grass share the same niche. park rangers plant seeds of both species on a hillside to prevent soil erosion. six months later, only one species of grass is present.