Select the best conjunctive adverb in the sentence below.
Every being, which during its natural lifetime produces several eggs or seeds, must suffer destruction during some period of its life, and during some season or occasional year;
, on the principle of geometrical increase, its numbers would quickly become so inordinately great that no country could support the product.
Darwin, Charles Robert. The Origin of Species. New York: P.F. Collier & Son, 1909–14,