Elastic Rubber has the highest value of Poisson's ratio among the given options.

Explanation:

Poisson's ratio is the ratio of lateral strain to the longitudinal strain in a material. It is a measure of the degree to which a material expands or contracts in the direction perpendicular to the applied force.

The value of Poisson's ratio varies from material to material. It can range from 0 to 0.5, where 0 represents a perfectly incompressible material and 0.5 represents a material that can be compressed to half its original volume.

Among the given options, elastic rubber has the highest value of Poisson's ratio. This is due to the unique properties of rubber, which is highly elastic and can undergo large deformations without breaking.

The value of Poisson's ratio for elastic rubber ranges from 0.49 to 0.5, which is close to the upper limit of 0.5. This means that elastic rubber can be compressed to half its original volume without breaking, making it a highly versatile material for various applications.

In contrast, wood, copper, and steel have lower values of Poisson's ratio, ranging from 0.2 to 0.35. This means that these materials are less compressible than elastic rubber and are more likely to break under large deformations.

In conclusion, elastic rubber has the highest value of Poisson's ratio among the given options due to its highly elastic and versatile properties.