Answer:
The <u><em>second </em></u>line of defense.
Explanation:
In our bodies the <em><u>second line of defense</u></em> includes active immunity. It contains non-specific immune responses, but yet still contains specific responses for certain things such as inflammatory and fevers.
In order to create a hydroelectric power plant, you need water, hence the prefix hydro-. Most times, people use dams to block the water, which in a way stores it. When you need to produce electricity, you release some of the water which flows through a turbine making it spin, which then activates a generator to produce electricity.
Inductive reasoning tanks!:)