When a hole of diameter d is punched in a metal of thickness 't', then the force required to punch a hole is equal to (where τu = Ultimate shear strength of the material of the plate)

A. d.t.τu

B. πd.t.τu

C. π/4 × d².τu

D. π/4 × d² × t.τu

Please do not use chat terms. Example: avoid using "grt" instead of "great".

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