Which of the following services allows you to run Microsoft Active Directory (AD) as a managed service

Answer options:

A.Simple AD
B.AD Connector
C.AWS Directory Service
D.Amazon Cloud directory

Answer - C
The AWS documentation mentions the following
AWS Directory Service lets you run Microsoft Active Directory (AD) as a managed service. AWS Directory Service for Microsoft Active Directory, also referred to as Microsoft AD, is powered by Windows Server 2012 R2. When you select and launch this directory type, it is created as a highly available pair of domain controllers connected to your virtual private cloud (VPC). The domain controllers run in different Availability Zones in a region of your choice. Host monitoring and recovery, data replication, snapshots, and software updates are automatically configured and managed for you.
For more information on the AWS Directory Service please visit the below URL:
http://docs.aws.amazon.com/directoryservice/latest/admin-guide/directory_microsoft_ad.html