Magnitude of primary productivity is affected by:

The correct option is D All of these
Primary productivity is the amount of biomass or organic matter synthesised by plants during photosynthesis per unit area over a time period. It depends on the plant species inhabiting i.e., living in a particular area. It also depends on a variety of environmental factors like temperature and solar radiation availability, availability of nutrients and photosynthetic capacity of plants. Therefore, it varies in different types of ecosystems.