The correct option is C Consumer
The rate at which these consumers convert the chemical energy of their food into their own biomass is called secondary productivity.
Primary productivity is the rate at which energy is converted by producers to organic substances.
Decomposition is the process by which organic substances are broken down into the simpler matter and not the formation of new organic matter.
Parasitism is a non-mutual relationship between species, where one species, the parasite, benefits at the expense of the other, the host/plant/consumer. And they are not involved in the formation of new organic matter.