Final answer:
For a 2-month development environment on the cloud, you can use On-Demand, Spot, or Reserved instances based on different factors.
Step-by-step explanation:
For hosting a development environment on the cloud consisting of EC2 and RDS instances for a 2-month duration, the types of instances that can be used are On-Demand instances, Spot instances, and Reserved instances.
On-Demand instances are best suited for short-term use as they provide flexibility and do not require long-term commitments. Spot instances can be advantageous for cost savings as they allow you to bid on unused Amazon EC2 capacity. Reserved instances offer significant savings when used for longer durations, but might not be the ideal choice for a 2-month period.