Technically, you are correct. The following combination of statements would indeed produce the inference you indicate:
The stimulus, however, is a bit more complex. Let's take a look:
- Soil Clay
Soil Sand or Organic Material
Clay Organic Material
The conclusion is not logically valid. Do you see why? If soil always contained both sand and
organic material, the conclusion would have been fine. However, apparently soil needs to contain one or
the other (or both) of these materials. Since only one of the two necessary conditions needs to be satisfied, it's possible that no soil contains sand (if all soil contained organic material), and it's also possible that no soil contains organic material (if all soil contained sand). Thus, no conclusion can plausibly be drawn on the basis of the information presented.
To attack this Parallel Flaw question, use this insight to identify an answer choice that contains the same error in reasoning.
Hope this helps!