Tortoises found on the Galapagos Islands can have varied phenotypes. One of the variations in the phenotypes is with regard to their shells. They can have a domed shell with a hood above the head. The shells without domes lack the hood above the head, such that the tortoise's neck is always pointing downward. A group of evolutionary biologists studied the tortoise population for generations on these islands. The study coincided with a severe drought in the area that lasted many years. The data for the changes in tortoise shell shape is shown here. Evaluate the data and select the statement that is best supported by this data. B

weathering is the answer.

when it is at an intermediate population density

it provides an alternative energy pathway for the reaction to proceed.

a catalyst is a substance that speeds up the rate of a chemical reaction but is not consumed during the course of the reaction.

catalysts increase the rate of reaction without being used up. they do this by lowering the activation energy needed. with a catalyst, more collisions result in a reaction, so the rate of reaction increases. different reactions need different catalysts.

a catalyst works by providing an alternative reaction pathway to the reaction product. the rate of the reaction is increased as this alternative route has a lower activation energy than the reaction route not mediated by the catalyst.