John and Pat are identical twins with identical DNA. John works in a movie theater, and Pat works as a lifeguard. They have very different skin pigmentation. Which is the best explanation of the difference? Skin color, a polygenic trait, is also determined by environmental factors.
Skin color, a polygenic trait, is also determined by the sex of the individual.
Skin color, a trait that demonstrates incomplete dominance, is also determined by environmental factors.
Skin color, a trait that demonstrates incomplete dominance, is also determined by the sex of the individual.

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explanation:

the answer is d. chordata

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.