What services should you leverage to enable an elastic …

A company is building a two-tier web application to serve dynamic transaction-based content.
The data tier is leveraging an Online Transactional Processing (OLTP) database.
What services should you leverage to enable an elastic and scalable web tier?

A.
Elastic Load Balancing, Amazon EC2, and Auto Scaling

B.
Elastic Load Balancing, Amazon RDS with Multi-AZ, and Amazon S3

C.
Amazon RDS with Multi-AZ and Auto Scaling

D.
Amazon EC2, Amazon DynamoDB, and Amazon S3