Explanation

Elasticity in AWS refers to the ability to automatically scale computing resources up or down based on demand. The two correct answers are:

1. The ability to rightsizing resources as demand shifts - This is a core aspect of elasticity where AWS services can automatically adjust resource capacity to match workload requirements.

2. How easily resources can be procured when they are needed - Elasticity enables rapid provisioning and de-provisioning of resources on-demand.

Why other options are incorrect:

• How quickly an Amazon EC2 instance can be restarted - This relates to instance recovery or reboot time, not elasticity.
• The maximum amount of RAM an Amazon EC2 instance can use - This refers to instance specifications, not elasticity.
• The pay-as-you-go billing model - This describes AWS pricing model (pay for what you use), which is related to but not the definition of elasticity.

Key Concept:

Elasticity is about scaling resources automatically in response to changing demand patterns, allowing you to maintain optimal performance and cost efficiency.