Two sites have one WAN Edge each. Each WAN Edge has two public TLOCs with no restrict configured. There is full reachability between the TLOCs. How many data tunnels are formed on each Edge router?

6 would represent the total number of unique TLOC-to-TLOC tunnels across the entire fabric (C(4,2) = 6), not the tunnels formed *on each* Edge router.

2 would only be formed if there was only one TLOC per router and only one remote TLOC to connect to, or if it only counted tunnels to the other router's first TLOC.

With two WAN Edges, each having two TLOCs and full reachability without restriction, each of the two local TLOCs will form a data tunnel with each of the two TLOCs on the remote WAN Edge. This results in 2 (local TLOCs) * 2 (remote TLOCs) = 4 data tunnels formed from a given Edge router to the remote site.

8 is incorrect; it suggests 2 local TLOCs forming tunnels with all 4 total TLOCs (2*4), which is incorrect because a TLOC does not form a tunnel with itself, and this overcounts bidirectional connections.