Vivian receives an e-mail notification from one of her software vendors that a new update is available. She decides to update a few servers at a time so that if there are any issues, she can address the issues on a small number of servers rather than all of the servers at once. She directs the traffic away from a few servers and, once those servers are updated, she starts sending traffic back to them, and then moves to the next wave of servers. Which of the following techniques is she using to apply this update? a. Rolling deployment
b. Blue-green deployment
c. Duplicate deployment
d. Canary deployment