किस भारी धातु के प्रदूषण के कारण मनुष्यों में 'इताई-इताई' (Itai-Itai) रोग होता 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)?