The WPBSA rules define "snookered" as the following:
17. Snookered
The cue-ball is snookered when a direct stroke in a straight line to every ball on is wholly or partially obstructed by a ball or balls not on. If one or more balls on can be hit at both extreme edges free of obstruction by any ball not on, the cue-ball is not snookered.
With this in mind, consider the following scenarios, where the red balls are "on":
| Name | Image | Comment |
|---|---|---|
| A |  |
The cue ball cannot hit the red ball on the extreme right edge, but the whole ball is "visible" from the point of cue ball. |
| B |  |
The red ball is partially obscured by the yellow. |
| C |  |
The "far" red ball is obstructed by the "near" red ball (which is obviously also "on"). If the nearer red ball is removed, the cue ball will not be able to strike the farther red ball on the extreme edge (scenario A). |
| D |  |
The "far" red ball is obstructed by both the "near" red and the yellow. If the nearer red ball is removed, the yellow red ball would partially obscure the farther (scenario B). |
| E |  |
The "far" red ball is obstructed only by other red balls. If the middle and nearest red balls are removed, the "possible angles" would be at least as wide as if the farthest ball was the only one. |
My question is: which of these scenarios are considered "snookered" by the rules (resulting in a free ball if encountered after a foul, etc.). Are there any other special cases I overlooked?
This question was inspired by the answers to these two questions which aren't clear in the matter, and also by this image on Wikipedia which states that the red is snookered by the black.
