A team is building an EMR Cluster in AWS. Management has requested that costs are optimized when working with the cluster. At the same time, you need to ensure capacity needs are met to ensure that EMR jobs are run as per demand. Which of the following can help you accomplish this? Choose 2 answers from the options given below

Answer options:

A.Use Spot Instances for the master, core and task nodes
B.Use an Instance fleet configuration for the EMR Cluster
C.Use a combination of On-demand and Spot Instances for Core and task nodes.
D.Use On-Demand Instances for the master, core and task nodes

Answer – B and C
The AWS Documentation mentions the following
The instance fleets configuration for a cluster offers the widest variety of provisioning options for EC2 instances. With instance fleets, you specify target capacities for On-Demand Instances and Spot Instances within each fleet. When the cluster launches, Amazon EMR provisions instances until the targets are fulfilled. You can specify up to five EC2 instance types per fleet for Amazon EMR to use when fulfilling the targets. You can also select multiple subnets for different Availability Zones. When Amazon EMR launches the cluster, it looks across those subnets to find the instances and purchasing options you specify.
While a cluster is running, if Amazon EC2 reclaims a Spot Instance because of a price increase, or an instance fails, Amazon EMR tries to replace the instance with any of the instance types that you specify. This makes it easier to regain capacity during a spike in Spot pricing. Instance fleets allow you to develop a flexible and elastic resourcing strategy for each node type. For example, within specific fleets, you can have a core of On-Demand capacity supplemented with less-expensive Spot capacity if available, and then switch to On-Demand capacity if Spot isn`t available at your price.
Option A is incorrect since using Spot Instances for the master node is not recommended
Option D is incorrect since this would not be the most cost effective option
For more information on Instance fleets, please refer to the below URL
https://docs.aws.amazon.com/emr/latest/ManagementGuide/emr-instance-fleet.html