Question

Since its formulation in the early twentieth century, the Neo-Darwinian synthesis has served as the foundational framework of evolutionary biology. This model asserts that evolutionary change is driven exclusively by random genetic mutations—alterations to the DNA sequence itself—which are subsequently acted upon by natural selection. Within this framework, environmental factors can influence an organism's phenotype during its lifetime, but acquired traits cannot be passed on to offspring; the germline remains strictly insulated from environmental vicissitudes.

In recent years, however, the burgeoning field of epigenetics has challenged this orthodox view. Epigenetic mechanisms, such as DNA methylation, regulate gene expression without altering the underlying nucleotide sequence. More provocatively, empirical evidence increasingly demonstrates that some of these environmentally induced epigenetic changes can be transmitted across generations. For instance, plants subjected to drought conditions can produce offspring that exhibit drought-resistant phenotypic traits, despite inheriting the exact same DNA sequence as the offspring of non-stressed control plants.

This phenomenon of transgenerational epigenetic inheritance has ignited fierce debate. Traditionalists, eager to preserve the primacy of the Neo-Darwinian model, argue that epigenetic changes are ephemeral. They maintain that because epigenetic marks are typically reset during embryogenesis, any transgenerational transmission is merely a short-term, "soft" inheritance that eventually reverts to the genetic baseline. Therefore, traditionalists contend, epigenetics requires no fundamental revision of evolutionary theory; it is simply a subsidiary mechanism of gene regulation ultimately controlled by the genetic sequence.

Yet, the traditionalist defense appears increasingly fragile in light of recent longitudinal research. Studies on nematodes have shown that environmentally induced epigenetic silencing can persist for up to fourteen generations, effectively driving adaptive population changes completely independent of DNA mutation. If such enduring epigenetic inheritance is discovered to be widespread across diverse taxa, the assumption that genetic sequence mutation is the sole engine of lasting evolutionary adaptation will be definitively falsified. It would therefore logically follow that __________.

Which one of the following most logically completes the argument in the passage?