Final answer:
The correct answer is option c. A decrease in the number of contracted attendees for a conference is known as attrition, and an attrition clause should be included in the conference service contract to address this situation and potential penalties.
Step-by-step explanation:
When a group decreases the number of contracted attendees for a conference, this is known as attrition. It's essential to have a provision in the conference service contract that addresses this issue. This attrition clause typically outlines the penalties or fees that will be charged if the actual number of attendees falls below the number that was initially agreed upon in the contract.
Moreover, having a clear mitigation of damages clause can also be beneficial. It encourages the group to notify the service provider of any changes as early as possible, allowing the provider to minimize lost revenue by reselling the space or services.