In the context of elastic theory of reinforced concrete, the modular ratio is defined as the ratio of

1. Young's modulus of elasticity of reinforcement material to Young's modulus of elasticity of concrete.
2. Young's modulus of elasticity of concrete to Young's modulus of elasticity of reinforcement material.

3. Shear modulus of reinforcement material to the shear modulus of concrete.

4. Young's modulus of elasticity of reinforcement material to the shear modulus of concrete.