Which of these queries will only include purchase records from the underlying table?

• SELECT campaign, COUNT(DISTINCT user_id) AS purchasers, SUM(purchases) AS purchases FROM amazon_attributed_events_by_traffic_time GROUP BY 1
• SELECT campaign, COUNT(DISTINCT user_id) AS purchasers, SUM(purchases) AS purchases FROM conversions GROUP BY 1
• SELECT campaign, COUNT(DISTINCT user_id) AS purchasers, SUM(purchases) AS purchases FROM amazon_attributed_events_by_traffic_time WHERE purchases = 1 GROUP BY 1

The correct answer is:

• SELECT campaign, COUNT(DISTINCT user_id) AS purchasers, SUM(purchases) AS purchases FROM amazon_attributed_events_by_traffic_time WHERE purchases = 1 GROUP BY 1