You run a web application where web servers on EC2 Instances are in an Auto Scaling group. Monitoring over the last 6 months shows that 6 web servers are necessary to handle the minimum load During the day up to 12 servers are needed five to six days per year, the number of web servers required might go up to 15.
What would you recommend to minimize costs while being able to provide hill availability?

A. 6 Reserved instances (heavy utilization). 6 Reserved instances {medium utilization), rest covered by On-Demand instances
B. 6 Reserved instances (heavy utilization). 6 On-Demand instances, rest covered by Spot Instances
C. 6 Reserved instances (heavy utilization) 6 Spot instances, rest covered by On-Demand instances
D. 6 Reserved instances (heavy utilization) 6 Reserved instances (medium utilization) rest covered by Spot instances