Statements:
1. All rivers are waters.
2. Some waters are oceans.
3. All oceans are vast.
Conclusions:
I. Some rivers are vast.
II. Some vast things are waters.
Correct: B
Let's represent the statements:
Statement 1: All rivers are waters. (Rivers circle is entirely inside Waters circle).
Statement 2: Some waters are oceans. (Oceans circle overlaps with a portion of the Waters circle).
Statement 3: All oceans are vast. (Oceans circle is entirely inside Vast circle).
From Statement 2 and 3: 'Some waters are oceans' and 'All oceans are vast'. This implies 'Some waters are vast'.
Now, let's analyze the conclusions:
I. Some rivers are vast. Rivers are inside Waters. Some Waters are Vast. However, the part of Waters that are vast might not include the Rivers. There's no definite link to conclude 'Some rivers are vast'. So, Conclusion I does not necessarily follow.
II. Some vast things are waters. This is a conversion of 'Some waters are vast', which we derived from the premises. If 'Some A are B', then 'Some B are A' is a valid conversion. Thus, Conclusion II follows.
Therefore, only conclusion II follows.