ऊर्जा संरक्षण में कौन सा व्यक्तिगत कार्य सबसे अधिक योगदान दे 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)?