Service dogs are often trained to assist in such tasks as letting their person know someone is at the door, safely crossing the street, or pusing buttons on the elevator. Which concept best describes how dogs were trained for these behaviors

Shaping

Explanation:

In simple words, Shaping can be understood as the practice of progressively rewarding closer by closer approaches to a targeted terminal behavior. A kid, for illustration, develops to pull himself up, standing, wander, and eventually move about by being reinforced for somewhat uncommon occurrences of action.

Thus, from the above we can conclude that the correct answer is shaping.