Final answer:
In an AP oblique projection of the lumbar spine, either the left or the right zygapophyseal (facet) joints will be visible, depending on which way the patient is obliqued. Both sides are not shown simultaneously; therefore, options 'a' or 'b' would be correct, based on the side of obliquity.
Step-by-step explanation:
The zygapophyseal (facet) joints demonstrated on the AP oblique projection of the lumbar spine are usually the ipsilateral superior and inferior articular processes of the spine. When a person is positioned in an AP oblique position, either the left or the right zygapophyseal joints will be visible depending on the direction of the obliquity. If they are obliqued to the right, the right zygapophyseal joints will be seen; if obliqued to the left, it will be the left ones. In the context of the provided options, the most accurate would be either 'a) Right superior and inferior' or 'b) Left superior and inferior' based on the side of the oblique position. However, without information about whether the oblique is left or right, it is not possible to choose between these two. It is clear, though, that option 'c) Both right and left' is incorrect because a single AP oblique view does not show both sides simultaneously. The answer is certainly not 'd) None' as zygapophyseal joints are indeed visualized in these projections.