Explain the process of classical conditioning with reference to a child's attachment to their parent

The Uncontrolled Stimulus (UCS) of a parent prior conditioning would not prompt a response of happiness (or attachment, the uncontrolled response) until it has been repeatedly paired with the neutral stimulus of food, provided by the parent. Once this has happened enough times, the UCS becomes the controlled stimulus of a parent's presence, eliciting the controlled response of happiness and attachment to the parent that provides the food.