A project has only four activities: A, B, C, and D. The duration of these activities are: 3, 5, 6, and 4 days, respectively. Activity A and B have no immediate predecessor. They can start as soon as the project starts. Activity C has activity A and B as its immediate predecessors. Activity B is the immediate predecessor of activity D. No work will be done on weekends and holidays. November 23, 2017, and November 24, 2017 are designated as holidays. If the project starts at the beginning of November 15, 2017, when will activity C be completed (actual date)? You must show brief calculation and explanation.