You are designing a solution based on the lambda architecture.
You need to recommend which technology to use for the serving layer.
What should you recommend?

A.
Apache Storm

B.
Kafka

C.
Microsoft Azure DocumentDB

D.
Apache Hadoop

Explanation:
The Serving Layer is a bit more complicated in that it needs to be able to answer a single query request against
two or more databases, processing platforms, and data storage devices. Apache Druid is an example of a
cluster-based tool that can marry the Batch and Speed layers into a single answerable request.
https://en.wikipedia.org/wiki/Lambda_architecture