Why is a race car traveling at a constant speed on a circular track an example of an object that is accelerating?
a. it is constantly speeding up
b. it is always slowing down
c. its direction is always changing
d. the engine is constantly providing the force to move it around the track

in 1859, charles darwin set out his theory of evolution by natural selection as an explanation for adaptation and speciation. he defined natural selection as the "principle by which each slight variation [of a trait], if useful, is preserved".

the most common type of reef is the fringing reef. this type of reef grows seaward directly from the shore. they form borders along the shoreline and surrounding islands.