The ability of plants to develop into several possible phenotypes depending on the environment they face is termed as :

Plasticity 

The correct answer is Option (3)- Plasticity

Plants follow different pathways in response to environment or phases of life to form different kinds of structures. This ability is called plasticity, e.g., heterophylly in cotton, coriander and larkspur.

In such plants, the leaves of the juvenile plant are different in shape from those in mature plants. On the other hand, difference in shapes of leaves produced in air and those produced in water in buttercup also represent the heterophyllous development due to environment . This phenomenon of heterophylly is an example of plasticity.