Oracle Cost Analysis charging block volumes within free tier

I am trying to estimate the costs for running a free oracle kubernetes cluster (basic) using A1 Ampere Nodes with 12GB RAM each.

When I selected the block volumes for those nodes - It is estimating 12.75 AUD price for both the volumes.

Each volume is 100GB in size totalling 200GB and the block volumes are within the free tier. I am attaching a screenshot of the cluster analysis.

Please let me know the best way forward. Please let me know how can I use the block volumes within the free tier as boot mount for the nodes in a kubernetes cluster.