Switches - Do I need Spanning Tree?
Solution 1:
Yes, this would be a loop for which you would need STP.
When you have trunks which don't carry all VLANs everywhere, you want to use some care in selecting the switch to be STP root. In particular, if either of the bottom switches is the STP root, then the top switches will resolve the loop by blocking the trunk forming the top of the box -- which is the only transit for VLAN 100 and 200, which I suspect is undesirable.