A material obeys hook’s law up to

Hooke's Law: Hooke's Law states that the stress in a material is directly proportional to the strain, as long as the material remains within its elastic behavior.

Elastic Limit: The elastic limit is the maximum stress a material can withstand without experiencing permanent deformation. Beyond this point, the material will not return to its original shape when the load is removed.

Plastic Limit: Incorrect, as this is the point where the material starts to exhibit plastic deformation, far beyond the elastic behavior.

Yield Point: Incorrect, as this is the point where noticeable plastic deformation begins, which is beyond the elastic limit.

Limit of Proportionality: Incorrect, as this is the point where the stress-strain curve begins to deviate from linearity, but the material may still obey Hooke's Law up to the elastic limit.

Conclusion: A material obeys Hooke's Law up to its Elastic Limit, making Option B the correct answer.