A company hosts a three-tier web application in the AWS Cloud. A Multi-AZ Amazon RDS for MySQL server forms the database layer Amazon ElastiCache forms the cache layer. The company wants a caching strategy that adds or updates data in the cache when a customer adds an item to the database. The data in the cache must always match the data in the database. Which solution will meet these requirements?

1. Implement the lazy loading caching strategy
2. Implement the write-through caching strategy
3. Implement the adding TTL caching strategy
4. Implement the AWS AppConfig caching strategy