The correct answer is B. Elasticity.

According to CompTIA A+ Core 1 220-1201 objectives under Networking and Cloud Concepts:

Elasticity refers to the cloud computing capability to automatically allocate and deallocate resources based on current demand. This ensures that applications have the necessary compute, storage, and network capacity during peak loads, and resources can be scaled down when demand decreases, optimizing efficiency and cost.

Why the other options are incorrect:

A. Hybrid deployment: Refers to using a combination of public and private clouds; it does not describe dynamic resource allocation.

C. Multitenancy: Describes the architecture where multiple users share the same infrastructure securely.

D. Metered utilization: Refers to charging based on resource consumption; it is a billing mechanism, not a dynamic allocation feature.