v₁₂ indicates that the poisson’s ratio that characterizes the decrease in ______ during tension applied in ______
a) 2- direction and 1- direction
b) 2- direction and 3- direction
c) 1- direction and 2- direction
d) 2- direction and 4- direction

Answer: a
Explanation: Poisson’s ratio is the ratio of transverse contraction strain to longitudinal extension strain in the direction of stretching force. Tensile deformation is considered positive and compressive deformation is considered negative.