पर्यावरण को बचाने के लिए इनमें से किस अभ्यास को सीधे तौर पर अपनाया जा सकता है?

Prolonged exposure to extreme cold temperatures may result in tissue damage known as frostbite, which is categorized as a:

In the context of ecosystem energy dynamics, which of the following expressions correctly defines Net Primary Productivity (NPP)?