Ava made a device that contains two chemicals: lye and a strong acid. When she activates the device, the acid is added to the lye. When these two chemicals mix, they react and produce heat.

To address the issues Ava is experiencing with her device, the solution lies in the way the acid is being introduced to the lye. The reaction between lye and the strong acid is exothermic, meaning it releases a significant amount of heat. If too much acid is added too quickly, it can lead to a rapid, intense reaction that generates excessive heat initially, followed by a rapid cooling as the reaction completes and dissipates heat.

To remedy this, the best option is:

**A. release the acid into the lye more slowly**

By adding the acid more slowly, Ava can control the rate of the reaction, producing a more gradual release of heat rather than a sudden spike. This should help stabilize the temperature and avoid the device becoming too hot too quickly, as well as prevent it from cooling down too rapidly.