Which will best ensure redundancy at the building distribution layer.

Explanation/Reference:
Layer 2 between distribution and access layers, with a Layer 3 link between the distribution switches
-> FHRP for convergence, no VLANs span between access layer switches across the distribution switches
Layer 2 between distribution and access layers, with a Layer 2 link between the distribution switches
-> Support Layer 2 VLANs spanning multiple access layer switches across the distribution switches
VSS
-> Convergence (FHRP) is not an issue