Write the three statements in standard form keeping subject → predicate order consistent:
$$S_1:$$ Some mirrors are glass.
$$S_2:$$ All glass are taps.
$$S_3:$$ Some taps are pens.
We now test each conclusion against these statements using the two basic rules of categorical logic that are always valid:
Rule 1 (Conversion for “Some A are B”): From “Some A are B” we can interchange subject and predicate to get “Some B are A.”
Rule 2 (Immediate statement acceptance): A conclusion that restates a given premise is always valid.
Testing Conclusion I: “Some glass are mirrors.”
Statement $$S_1$$ is “Some mirrors are glass.” By Rule 1 we may convert it to “Some glass are mirrors.” Therefore Conclusion I logically follows.
Testing Conclusion II: “All taps are glass.”
Statement $$S_2$$ says “All glass are taps,” which is a one-way inclusion. The converse “All taps are glass” is not guaranteed by the original statement, so Conclusion II does not follow.
Testing Conclusion III: “Some pens are taps.”
Statement $$S_3$$ itself is “Some taps are pens.” Converting by Rule 1 would give “Some pens are taps,” exactly our conclusion. Hence Conclusion III follows.
Therefore only Conclusions I and III follow.
Option D which is: Only conclusions I and III follow.