It's B - Access Control Policy
I think that mentioned "cloud environment" in the question is just catch. Rest of the question is all about USERS, their authentication, authorization, POSTURE (you are not posturing applications or workloads in the cloud but users), deny/allow applications - TrustSec policy - all about ISE.
Microsegmentation is related to APPLICATIONS and WORKLOADS, I haven't found any mention about USERS.
"Micro-segmentation creates secure zones across cloud and data center environments to isolate application workloads from one another and secure them individually. With micro-segmentation, firewall policies limit east-west traffic between workloads based on a zero-trust security approach to reduce attack surfaces, prevent the lateral movement of threats to contain breaches, and strengthen regulatory compliance. Micro-segmentation is also referred to as application segmentation or east-west segmentation in a multicloud data center."
https://www.cisco.com/c/en/us/products/security/what-is-microsegmentation.html