You are building a content-serving web application with 20 EC2 instances. The EC2 servers are all load-balanced, and content storage for the instances will remain the same.
You have chosen AWS EFS to act as a common storage repository. Your application needs to have as low of latency as possible when serving content to the web users. Which of the following options is the best choice for this situation?

Answer options:

A.Max I/O Performance Mode
B.General Purpose Performance Mode
C.Bursting Throughput Mode
D.Provisioned Throughput Mode

Answer: B
Although Max I/O is recommended to be used when tens, hundreds, or thousands of EC2 instances sharing the same EFS, it can slightly increase the latency. In this case, the question states the latency needs to be as low as possible.
Performance Modes
To support a wide variety of cloud storage workloads, Amazon EFS offers two performance modes. You select a file system`s performance mode when you create it.
The two performance modes have no additional costs, so your Amazon EFS file system is billed and metered the same, regardless of your performance mode. For information about file system limits, see Limits for Amazon EFS File Systems.
Note: An Amazon EFS file system`s performance mode can`t be changed after the file system has been created.
General Purpose Performance Mode
We recommend the General Purpose performance mode for the majority of your Amazon EFS file systems. General Purpose is ideal for latency-sensitive use cases, like web serving environments, content management systems, home directories, and general file serving. If you don`t choose a performance mode when you create your file system, Amazon EFS selects the General Purpose mode for you by default.
Max I/O Performance Mode
File systems in the Max I/O mode can scale to higher levels of aggregate throughput and operations per second with a tradeoff of slightly higher latencies for file operations. Highly parallelized applications and workloads, such as big data analysis, media processing, and genomics analysis, can benefit from this mode.
https://docs.aws.amazon.com/efs/latest/ug/performance.html#performancemodes
Via the explanations above, Option B is the only correct statement.
For Bursting and Provisioned Throughput modes, please refer to page 85 to 89 on the below link:
https://docs.aws.amazon.com/efs/latest/ug/efs-ug.pdf