Economist feel the best way to evaluate the cost of a decision is to consider EVERY possible alternative choice.

answer; /// i believe the correct answer is (reactants);

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".

answer; the male's sperm cells have mitochondria, but because the sperm contributes dna but no cytoplasm, no mitochondria are passed to the egg at ferilization;