AWS

Both DynamoDB and ElastiCache provide high performance storage of key-value pairs. CloudWatch and ELB are not storage services. Storage Gateway is a storage service, but it is a hybrid storage service that enables on-premises applications to use cloud storage.

EBS Provisioned IOPS SSD provides sustained performance for mission-critical low-latency workloads. EBS General Purpose SSD can provide bursts of performance up to 3,000 IOPS and have a maximum baseline performance of 10,000 IOPS for volume sizes greater than 3.3 TB. The 2 HDD options
are lower cost, high throughput volumes.

Amazon Aurora is a relational database that will automatically scale to accommodate data growth. Amazon Redshift does not support read replicas and will not automatically scale. DynamoDB is a NoSQL service, not a relational database. Amazon S3 is object storage, not a relational database.

If a versioned object is deleted, then it can still be recovered by retrieving the final version. Response A would lose any changes committed since the  revious snapshot. Storing the data in 2 S3 buckets would provide slightly more protection, but a user could still delete the object from both buckets. EC2 instance storage is ephemeral and should never be used for data requiring durability.

IAM roles for EC2 instances allow applications running on the instance to access AWS resources without having to create and store any access keys. Any solution involving the creation of an access key then introduces the complexity of managing that secret.