Biotic mean alive, so we can cut off the first 2 easily. Aquatic birds eat frogs, so that one is safe for now. A decrease in something parasitic usually helps the population, so D is out too. The only one left is C.
measure of the intrinsic luminosity of a celestial body (such as a star) expressed as the apparent magnitude the body would have if viewed from a distance of 10 parsecs.
