Answer: I know that tighter, “less sloppy” turns will create a more effective electromagnet; using more power would be better as well; but if I don’t have that choice, I would have choose a more carefully wound copper wire, BUT since it does work as it is, get a more powerful battery.
Step-by-step explanation:
I see your dilemma; I would change more than I am allowed by the question; a larger nail is no better if the wound copper wire is sloppy, unless more power is given; but if all the variables were maximized, the magnet would be much better. I think it would be a good idea to check which is the more powerful battery, more power can make up for less than ideal work here; but I am not certain if a D or C battery is more powerful! If a C battery is more powerful, it would at least increase the number of paper clips.