(d) : Net primary productivity is the total organic matter stored by producers per unit area per unit time. Gross primary productivity is the total organic matter synthesised by producers in the process of photosynthesis per unit area per unit time.

So,Net primary productivity = Gross productivity -Respiration and other losses Tropical rainforests occur over equatorial/ subequatorial regions with abundant warmth andrainfall. Diversity and productivity are maximum ascompared to other regions.