If I had a third arm, I think that I would be in shock if it appeared overnight. However if I were born with it, it would be as much a part of me as my big toe is a part of my foot. However, the question is asking me to choose the placement of this third arm, so apparently I have to decide where it goes, meaning that I wasn’t born with it, so I have to make the best of it and place it where it would make the most sense and for vanity’s sake, the least ugly.
I am clumsy enough with the appendages I do own, I don’t see how I’m going to keep a new addition any safer than the ones already on me. If I had my third arm in between my other two, typing might go faster, cooking might be easier and more efficient, driving might be less dangerous because I would always have at least two hands on the wheel. The third arm safely ensconced between the other two might actually keep it out of harm’s way. I’m already aware of the location and existence of the first two arms, so the addition of the third in the same vicinity would be relatively easy for my brain to process. If I ever fell or slipped, I would have an additional hand to catch me or catch on to something to keep me from falling. For appearances sake, it would be odd having a third arm placed in between my breasts, but the third arm would look equally awkward in the middle of my back or attached at my hip or on my thigh. I ‘m fairly sure that for efficiency the arm in the middle of the other two is the way to go. I’m very glad that this is all hypothetical, I wouldn’t want this to really happen.