Spanning Tree Protocol (STP) is used specifically in Ethernet Layer 2 networks to prevent loops caused by redundant paths.

STP detects loops and blocks one or more redundant paths to ensure there is a loop-free topology in a bridged network.

STP dynamically recalculates the topology if a link fails, reactivating previously blocked paths.

Explanation of other options:

A . MPLS with LSPs: MPLS uses its own mechanisms for path management, such as RSVP or Segment Routing. STP is not applicable here.

C . OSPF with ECMP (Equal-Cost Multi-Path): OSPF is a Layer 3 protocol that inherently supports multiple paths without loops; STP is not involved.

D . eBGP (Exterior Border Gateway Protocol): Operates at Layer 3 for inter-AS communication; STP is not used in BGP routing.

Therefore, Option B is correct, as STP is explicitly designed for Layer 2 Ethernet networks with redundant paths.

Nokia IP Networking Fundamentals Study Guide -- Chapter: 'Layer 2 Technologies'

IEEE 802.1D Standard -- Spanning Tree Protocol Overview