The answers are correct. Multiple resource locks (in the form of Delete or Read-only) can be applied to a resource. These allow the different entities to use the lock of the resource-based on their required purpose. Eg Entity A locked VM1 and Entity B locked VM1 with their respective lock. Entity A might not require the lock but Entity B still require it. Furthermore due to lock policy apply at higher hierarchy to be enforced eg Management group apply lock on all VM even lower level resource group.

You can set the lock level to CanNotDelete or ReadOnly. In the portal, the locks are called Delete and Read-only respectively.

CanNotDelete means authorized users can still read and modify a resource, but they can't delete the resource.
ReadOnly means authorized users can read a resource, but they can't delete or update the resource. Applying this lock is similar to restricting all authorized users to the permissions granted by the Reader role