निम्नलिखित में से कौन सा धरातलीय (क्षोभमंडलीय) ओजोन के मापन की इकाई नहीं 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)?