The best delivery method to support the client's requirement is C. Subscription.
Short explanation: A subscription is a delivery method that allows the client to access the dashboard on- demand, whenever they need it. A subscription can be set up by the data analyst or the client themselves, and it can be configured to send an email notification when the dashboard is updated or refreshed. A subscription also allows the client to view the dashboard online or download it as a file format of their choice12 A: Email is not the best delivery method because it does not allow the client to access the dashboard on- demand. Email deliveries are sent at a fixed time or frequency, and they may not reflect the latest data or changes in the dashboard. Email deliveries also have limitations on the file size and format of the dashboard attachments1 B: Scheduled is not the best delivery method because it does not allow the client to access the dashboard on- demand. Scheduled deliveries are similar to email deliveries, except that they are triggered by a specific event or condition, such as a data update or a threshold value. Scheduled deliveries also have the same limitations as email deliveries on the file size and format of the dashboard attachments1 D: Static is not the best delivery method because it does not allow the client to access the dashboard on- demand. Static deliveries are one-time deliveries that are manually generated by the data analyst or the client.
Static deliveries do not update or refresh automatically, and they may become outdated or irrelevant over time. Static deliveries also have limitations on the file size and format of the dashboard files3