During the Lead Conversion process, Salesforce automatically transfers the history and interaction data associated with the Lead to the newly created Account, Contact, and Opportunity. This includes all activities, meaning both Open Activities (like upcoming tasks or events) and Activity History (like past emails or logged calls) are attached to the resulting records to maintain a complete customer timeline. Campaign history is also typically associated with the resulting Contact, but the question specifically asks about " related records " in a broader sense, and the transfer of all activities is a primary mechanical function of the conversion. Option A is incorrect because custom object records do not automatically move unless specific custom mapping or code is in place. Option B is incorrect because the system does not limit the transfer to only open activities.