A disturbing mass m₁ attached to the rotating shaft may be balanced by a single mass m₂ attached in the same plane of rotation as that of m₁, such that (where r₁ and r₂ are the radii of rotation of m₁ and m₂ respectively)

A. m₁r₂ = m₂r₁

B. m₁r₁ = m₂r₂

C. m₁m₂ = r₁r₂

D. None of these

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