For a promotion that rewards members for making three purchases in a single month, the appropriate type of Loyalty Promotion to use would be:

Cumulative Promotion (B):This type of promotion is designed to reward members for cumulative actions over a specified period, such as making multiple purchases within a month. It tracks and accumulates qualifying activities, issuingrewards once the defined criteria are met, making it ideal for encouraging sustained engagement and repeat transactions.

Options A (Standard Promotion), C (Joint Promotion), and D (Aggregate Promotion) do not specifically cater to the requirement of rewarding members for multiple actions within a set timeframe, making Cumulative Promotion the most suitable choice for this scenario.

Salesforce documentation on Loyalty Management would provide detailed information on different types of promotions, including how to set up and manage a Cumulative Promotionto drive engagement and reward member loyalty effectively.