The correct answer is Multitenancy.

Multitenancy means that multiple customers share the same physical or virtual infrastructure and that shared nature can allow an attacker who gains access to underlying systems to impact other tenants. This characteristic creates risks from insufficient isolation, noisy neighbor effects, side channel attacks, and lateral movement across tenants when controls fail.

Rapid elasticity refers to the ability to scale resources quickly to meet demand and it does not inherently cause other tenants to be compromised. Scalability affects how resources are provisioned and released rather than how they are isolated.

On demand self service describes the ability of customers to provision and manage resources without provider intervention and it addresses convenience and agility rather than shared-host security risks between tenants.

Reversibility is about the ability to migrate data and services away from a provider or to restore a prior state and it relates to portability and exit strategies rather than cross-tenant compromise.

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