Company a Builds a Sales Management Platform Based on Alibaba

Multiple Choice

Company A builds a sales management platform based on Alibaba Cloud services, using 3 ECS instances. One of the ECS instance has MySQL installed as the database server of the platform, the other two are used as WEB servers. After some time, due to the rapid increase of employees and sales analysis requests, the performance of the platform is challenged in terms of response time. Through CloudMonitor, it is found that the average CPU usage reaches 70% for the two WEB server ECS instances and the database load reaches 75% for the database server ECS instance. In this situation, company A may choose which Alibaba Cloud services to improve the performance _________________. (Choose two.)

A) Use content delivery network, CDN, to accelerate the caching of the platform's css, JavaScript files etc.
B) By adding a SLB instance and increase the number of ECS instances to reduce the work load on current ECS instances.
C) Use RDS to replace existing self-built database, in order to obtain better database performance; also creating RDS read-only instances to handle read-only requests, hence reduce the work load on master RDS instance.
D) Import data into OSS to share the storage load of the platform.