You are working for a company which is about setting up a country-wide environmental monitoring system for real-time air pollution monitoring. The system consists of 10000 sensor end-devices sending a large amount of telemetry data to several IoT hubs. There are several back-end services connected to these hubs to process and analyze the ingested data to provide near real-time forecasts. To cope with requirements and to avoid concurrency issues between consumer services, you want to build the solution on the partitioning feature of the IoT Hub. 
Which two things should you keep in mind while planning to use multiple partitions?

Answer options:

A.RPO and RTO
B.The order of processed events
C.Throughput limit of a partition
D.The expected number of concurrent consumers
E.The tier and edition of IoT hub

Correct Answers: B and D
Option A is incorrect because Recovery Point Objective and Recovery Time Objective refer to the recoverability of the system after a disaster. They are disaster recovery metrics and they are not related to the event processing capacity.
Option B is CORRECT because when having more than one partition, the incoming data will be sent to multiple partitions without preserving their original order. If the order of events matters, you need to configure your solution with this potential issue in mind.
Option C is incorrect because partitions don’t have specific throughput limits. It is the aggregate throughput that is limited by the number of throughput units. Note that the number of partitions cannot be altered after the IoT Hub has been created!
Option D is CORRECT because one of the key things to consider when choosing the right number of partitions is the expected number of bac-end services that will read the event strings concurrently. The number of IoT Hub partitions can only be set on creation, therefore it requires thorough planning.
References: 

https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-scaling#partitions
https://docs.microsoft.com/en-us/azure/event-hubs/event-hubs-faq#how-many-partitions-do-i-need