As we know that power is defined as rate of work done
so we will have

so in order to increase the power as per above formula we know that either we need to increase the work or we need to decrease the time to complete that work
So here the correct answer will be
increase the work being done or decrease the time in which the work is completed.
a. all systems work together to stabilize the body
During a single replacement, the Zn and H will switch places. That means the product formed will be ZnCl and H2.
Water boiling is an example of a physical change. The rest are chemical changes.
Hope that helps!!