Correct Answer - B.
DAX is intended for applications that require high-performance reads.
As a write-through cache, DAX allows you to issue writes directly so that your writes are immediately reflected in the item cache.
You do not need to manage cache invalidation logic because DAX handles it for you.
For more information, please check the below link-
https://docs.aws.amazon.com/amazondynamodb/latest/developerguide/dynamodb-dg.pdf
Option A is incorrect.
Write Around Cache is generally useful when there is a considerable amount of data to be written to the database.
In this case, data is directly written to DynamoDB instead of DAX.
Option C is incorrect as Using Side Cache using Redis is eventually consistent and non-durable which may add additional delay.
Option D is incorrect.