Which structure could be found in a single-celled organism? intemal organs legs and feet outer covering large brain

A solitary called life form would have an external covering in particular. Clarification: Having a brain, legs and inner organs is excessively perplexing for a unicellular organism(organisms with one cell)

Explanation:

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.

i think it is d. objects resist changes in their state of motion.