If w is the displacement in z-direction, the linear strain component in is defined by __________

• A. \(ε_Z=\frac{∂w}{∂z}\)
• B. \(ε_Z=\frac{∂z}{∂w}\)
• C. \(ε_Z=\frac{dz}{dw}\)
• D. εZ=z+w