Step 1: Concept Chaff cutters are used to cut fodder into small pieces for livestock feeding.
Step 2: Meaning The blades must be thick enough to maintain their edge and withstand the impact of cutting fibrous stalks without bending.
Step 3: Analysis Standard engineering specifications for agricultural chaff cutter blades generally require a minimum thickness to ensure safety and longevity.
Step 4: Conclusion According to standard design parameters, the minimum thickness is 4.4 mm.
Final Answer: (D)