Which Equation Would Be Described as a Single Displacement Reaction $\rightarrow$

Which equation would be described as a single displacement reaction?

A) 2 CO + O₂ $\rightarrow$ 2 CO₂
B) CuCO₃ $\rightarrow$ CuO + CO₂
C) 2 AgNO₃ + Na₂CrO₄ $\rightarrow$ Ag₂CrO₄ + 2 NaNO₃
D) Zn + Cu(NO₃) ₂ $\rightarrow$ Zn(NO₃) ₂ + Cu