Option A: We know all pens are instruments. However, this does not mean that all instruments are pens. Thus, option A is not necessarily true. Option B: Correct. As can be seen from the Venn diagrams, if some green things are instruments then it follows that some instruments are green. Option C: We only know that some green things are instruments. From this we cannot draw any conclusion regarding the relation between pens and green things.
Option D: As explained above, we cannot establish a conclusive relationship between pens and green things.
Option E: Only statement (3) is correct.
So, the correct answer is B.