The $$1,500$ toaster was equipped with sensors that could detect a spike in electricity, the moisture and density of the bread, and the relative humidity. It also scanned each piece of toast it made and compared it to the ideal and the customer setting It became smarter with each piece of toast produced, stopping just short of becoming self$-$aware. The improvement capability built into this device is an example of

a$.$ sentient resilience.

b$.$ engineering resilience.

C$.$ adaptive resilience.

d$.$ operational resilience.