Thank you so much for your help Macman.
I have gone back to the drawing board with this question and due to your help have come to some more conclusions.
c. 1,3-Dichlorobutane + sodium iodide (1 mole) in acetone - As NaI is soluble in acetone, and the I- could substitute the 1-chloro- THIS IS MY NEW CHOICE!
d. 1,3-Diiodobutane + sodium chloride (1 mole) in acetone - After researching the productivity of NaCl in acetone I learned that it is insoluable, therefore this is also SCRATCHED
e. 3-Bromo-1-iodobutane + sodium chloride (1 mole) in acetone - I have researched leaving group priority and learned that Cl-<Br-<I- therefore I think it would be safe to say that in this reaction 1-iodo would leave first, therefore not giving the correct 3-chloro-1-iodobutane as a product... so this option is now SCRATCHED.
Therefore after more work, and I am so grateful for your help... I would have to propose that c is the correct answer.