What is the stress term called which is a measure of the stiffness or resistance to deflection? Modulus of Elasticity (E)
Extreme Fiber Bending (F )
Horizontal Shear Parallel to the Grain (F //)
Compression Perpendicular to the Grain (F z )

Modulus of Elasticity (E) A

Explanation:

The modulus of elasticity, Young's modulus E is a measure of a material's stiffness or resistance to being elastically deformed when stressed or due to tension According to  Hook's law the modulus of elasticity is defined as the ratio of the stress to the strain and defined as the slope of its stress-strain region  in the stress and strain graph.

--The stiffer a material, the higher the elastic modulus and vice versa for a less stiff material.

it can be calculated with this formulae

Young’s modulus equation is E = tensile stress/tensile strain

= (FL) / (A X change in L)

where F = applied force,

L = initial length,

A = square area,

E = Young’s modulus in Pascals (Pa).