Resiliency is defined as the ability to
a. run
b. relax
c. set goals
d. bounce back

Resiliency is the ability to bounce back.

d. bounce back

Explanation:

It's the capacity of the ecosystem to respond to disturbances in the environment and recover quickly, it's considered as the natural ability of the ecosystem and bounce back to its original default position. It can also be termed as a feedback mechanism to the system that has multiple stable regimes. Such as the prevalence of shallow temperature existing at a greater depth of the ocean be seen as cleaning water regimes for reducing the toxic algae blooms. Ecologists Brian Walker, C S Holling gave this concept as ecosystem resilience.