प्रदूषण रहित परिवेशी वायु में कार्बन मोनोऑक्साइड (CO) की सामान्य पृष्ठभूमि सांद्रता सीमा (background concentration range) क्या 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)?