The correct answer is C. Elasticity . In cloud computing, elasticity refers to the ability to increase or decrease resources quickly based on current demand . If workloads rise, more compute resources can be allocated. If demand drops, those resources can be reduced again. That is exactly what the question is describing.
This is slightly different from scalability . Scalability is the broader idea that a system can grow to handle more workload. Elasticity focuses more on the dynamic, on-demand adjustment of resources as conditions change. In exam questions, wording like "add or remove based on need" usually points straight to elasticity.
The other answer choices do not fit. Availability is about uptime and service access. Multitenancy refers to multiple customers sharing underlying cloud infrastructure while remaining logically separated. Neither describes rapid expansion and contraction of compute resources.
From a Network+ study perspective, elasticity is one of the core cloud characteristics to remember because it explains why cloud services are useful for workloads that are unpredictable or variable. Instead of permanently building for peak demand, organizations can consume more or less compute as required. That makes elasticity the best answer.