Couple of things.
Every item in the left-hand pane can be considered a 'mod' so:
Unmanaged: Dawnguard is a mod
cleaned Dawnguard.ESM is a mod (even though this is essentially the same file as from Unmanaged: Dawnguard , just cleaned)
Dawnguard Textures opt is a mod
Unofficial Dawnguard Patch is a mod
Things that pass the 'conflict' examination
ModA has some files: Texture1, Texture2, Texture3, Texture4, Texture5, Texture6, PluginA
ModB has just one plugin: PluginC
ModC has some other files: Texture4, Texture5, Texture7,
ModD, more files again: Texture1, Texture2, Texture3, PluginA, PluginB
Assuming those mods are in that order in the left-hand pane the files that get through to be used in the game are the ones highlighted.
ModB's file PluginC gets through the conflict because, although there are two other mods lower than it, they contain no conflicting files, it is the only one that contains PluginC.