Some fuel cells are powered by hydrogen. scientists are looking into the decomposition of water (h2o) to make hydrogen fuel with the of the sun’s energy. what challenge do scientists face with this task? a. decomposing water requires a high activation energy. b. the sun isn't a renewable resource. c. decomposing water results in toxic byproducts. d. scientists are uncertain what to do with the excess oxygen.

A. Decomposing water requires a high activation energy.

Explanation:

The leftovers of the division of the molecule of water would be Hydrogen that would be used as fuel, and oxygen which is necessary and its benefical for humans, so there would be no toxical residuals, and the residuals could be thrown to the air, so the most challenging thing that the scientist would face would be the fact that the molecule of water has a really strong bond between the oxygen and the two atoms of hydrogen, so it requires a really high activation energy.

i am pretty sure it is c because when people are closer together, they cannot move as freely. picture being in a mostly full elevator, for instance. the people are right next to you, and you can barely move.