Your network contains four Active Directory forests. Each forest contains an Active Directory Rights
Management Services (AD RMS) root cluster.
All of the users in all of the forests must be able to access protected content from any of the forests.
You need to identify the minimum number of AD RMS trusts required.
How many trusts should you identify?
A.
3
B.
6
C.
12
D.
16
Correct.
The number of AD RMS trusts required to interact between all AD RMS forests can be defined by using the following formula: N*(N-1).
For example, if you have 4 AD RMS forests and all of them should be allowed to exchange information between each other, then – 12 (4X (4-1)) AD RMS trusts will need to be configured to achieve this.
https://technet.microsoft.com/en-us/library/dd772659(v=ws.10).aspx