Question

What is the role of the grass? primary producer secondary producer primary consumer secondary consumer

Answer 1

Primary producer is the answer. 
  
Here is the definition. 

Primary producers are organisms in an ecosystem that produce biomass from inorganic compounds (autotrophs). In almost all cases these are photosynthetically active organisms (plants, cyanobacteria and a number of other unicellular organisms.

Answer 2

The role of grass is the primary producer because it is the beginning of almost every food chain.