The correct answer is C. elasticity.
Elasticity is the ability of a system to adapt to changes in demand. In the context of a database, elasticity allows you to add or remove resources as needed to meet the demands of your application. This can be done automatically, without any manual intervention, which can save you time and money.
Scalability is the ability of a system to handle an increasing amount of data or users. In the context of a database, scalability allows you to add more storage or processing power as needed to keep up with the growth of your application.
Reliability is the ability of a system to perform its intended function without interruption. In the context of a database, reliability means that your data is always available when you need it.
None of the other options are correct.