The correct answer is Increase speed and agility because:

• Speed and agility refers to the ability to rapidly provision and deploy resources, which directly supports the requirement to "develop, test, and launch an application quickly"
• In cloud computing, organizations can spin up resources in minutes rather than weeks or months required for traditional IT infrastructure
• This advantage allows companies to accelerate their development lifecycle and respond quickly to market demands

Why other options are incorrect:

• Stop guessing capacity: Focuses on capacity planning and resource optimization, not speed of deployment
• Trade fixed expense for variable expense: Relates to cost management and payment models, not development speed
• Achieve economies of scale: Concerns cost benefits from large-scale operations, not rapid application deployment