Pepper's Pizza is owned by Paulie Pepper. It is a popular restaurant partially because Pepper's guarantees that their pizzas will be delivered within forty$-$five minutes of when it is ordered, or the customer gets it free. To ensure that they get the pizzas delivered on time, they have drivers who are employees of Pepper's. One of these drivers is Charles Earnhardt. When the ordinary drivers are busy, they also use Restaurant$-$to$-$You, a food delivery service. Restaurant$-$to$-$You is an independent contractor to Pepper's Pizza.

Which of the following doctrines would possibly allow Earnhardt's negligent driving to put liability on Pepper's Pizza?