In this food chain, grass is the producer and rabbit is the primary consumer, as it directly feeds on the grass. The fox is the secondary consumer as it feeds on the rabbit.

Option 1: Decomposer Food Chain - This type of food chain includes decomposers like bacteria and fungi which break down dead organic matter. There are no decomposers mentioned in the given food chain, so this option is incorrect.

Option 2: Detritus Food Chain - This type of food chain includes detritivores that feed on dead organic matter. Again, there are no detritivores mentioned in the given food chain, so this option is incorrect.

Option 3: Grazing Food Chain - This option is correct. A grazing food chain involves plants being consumed by herbivores, which are then consumed by carnivores. This matches the given food chain.

Option 4: Parasitic Food Chain - This type of food chain involves parasites feeding on the host. There is no mention of parasites in the given food chain, so this option is incorrect.

In conclusion, the correct type of food chain for the given example is a grazing food chain.