**Explanation:**

Poisson's ratio is a measure of the deformation that occurs perpendicular to an applied force. It is defined as the ratio of the transverse strain to the longitudinal strain. Poisson's ratio is always a positive value between -1 and 0.5 for most common materials.

**Definition of Poisson's Ratio:**

Poisson's ratio (ν) is defined as the ratio of the lateral strain to the longitudinal strain within the elastic limit of a material. It is given by the formula:

ν = - (lateral strain/longitudinal strain)

where,
- ν is the Poisson's ratio
- Lateral strain is the strain in the direction perpendicular to the applied force
- Longitudinal strain is the strain in the direction of the applied force

**Explanation of Options:**

a) Cork: Cork is a lightweight material derived from the bark of the cork oak tree. It is an elastic material with a Poisson's ratio typically ranging from 0 to 0.3. Therefore, cork does not have a Poisson's ratio greater than 1.

b) Wood: Wood is a natural composite material made up of cellulose fibers embedded in a matrix of lignin. Different types of wood can have different Poisson's ratios, but they generally range from 0.2 to 0.4. Wood does not have a Poisson's ratio greater than 1.

c) Plastic: Plastic materials have a wide range of properties, including different Poisson's ratios. However, the Poisson's ratio of plastics typically falls within the range of 0.3 to 0.5. Plastic does not have a Poisson's ratio greater than 1.

d) None: None of the materials mentioned in the options (cork, wood, or plastic) have a Poisson's ratio greater than 1. Therefore, the correct answer is option 'D' - None.

In conclusion, the correct answer is that none of the mentioned materials (cork, wood, or plastic) have a Poisson's ratio greater than 1.