Climate change is affecting the chemistry of the world's oceans. In particular, the ocean water is becoming more acidic. For purple sea urchins, this poses problems as their calcium-based exoskeletons may dissolve in acidic conditions. In a certain population of purple sea urchins, some individuals possess a trait that makes their exterior more resistant to acid. If global climate change continues (as predicted) to make ocean water more acidic, how might this population of purple sea urchins evolve in response to this increased acidification?

This statement contradicts the principles of natural selection. If purple sea urchins have exoskeletons that are less resistant to acid, they are at a greater risk of mortality in acidic conditions, making it unlikely for them to thrive or reproduce compared to their more resistant counterparts.

While longer, more rigid spines may offer some advantages, they do not directly address the pressing issue of acidification affecting the dissolution of calcium-based exoskeletons. The evolution of spine length is unrelated to the survival of the species in a more acidic environment.

Similar to choice C, this option discusses spine characteristics that are not directly linked to the survival challenge posed by increased ocean acidity. Spine flexibility does not provide a solution to the dissolution of the exoskeleton and, therefore, does not contribute to the evolutionary adaptation necessary in this scenario.