Comprehensive and Detailed Explanation From Exact Extract:

In a leaf-spine Clos network:

Option A is TRUE: Each leaf connects to every spine for full redundancy and non-blocking fabric.

"In a Clos topology, every leaf node connects to every spine node, ensuring any-to-any connectivity."

— Nokia Data Center Fabric Design Guide, "Leaf-Spine Architecture"

Option B is TRUE: East-west traffic flows predictably via spines.

"Leaf-spine provides deterministic paths for east-west traffic, minimizing latency and jitter."

— Nokia SR Linux EVPN Configuration Guide, "Traffic Flow in Clos Networks"

Option C is FALSE: Clos networks do not use STP. They rely on Layer 3 ECMP and routing protocols for loop avoidance.

"Clos fabrics eliminate STP by design. Forwarding loops are avoided through ECMP and routing protocols (e.g., BGP), not Layer 2 STP."

— Nokia Data Center Fabric Best Practices, "Loop Avoidance"

Option D is TRUE: ECMP load-balances traffic across multiple spine paths.

"ECMP is fundamental to leaf-spine, distributing traffic across all available spine links."

— Nokia SR Linux Routing Guide, "ECMP in Clos Fabrics"