If a catalyst lowers the activation energy, what raises the activation energy? heat
a reaction
another catalyst
an inhibitor

an inhibitor

Explanation:

An inhibitor will raise the activation energy of a chemical system because it works in the opposite way a catalyst works.

A catalyst is any chemical substance the increases the rate of chemical reaction. They simply bind the substrate and bring them into reaction instead of passing through the high energy peaks.

An inhibitor works in an opposite way. They raise the activation energy of a reaction and prevents a reaction from taking place.

precipitation

explanation:

when it goes from cloud to rain/back to earth in the form of rain