Both options A (Contact) and D (Lead) are correct. These objects are used in Salesforce. The campaigns help link together initiatives for marking, and any leads that can come about from the marketing done. There are many features and advantages to campaign managers. It will enable the user to organize the campaigns to know what is generating more revenue and working well. It also allows for quick access to campaigns and to keep everything organized and easy to access.
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Also, watch this video on Campaigns in Salesforce: