Answer:
a. Assuming an investor prefers the extra $0.50 per year, then he/she can invest the $5 received as special dividend and earn $0.50 himself/herself in the same or similar risk free investment.
b. If the investor needed or wanted the $5 instead of $0.50 extra per year, he/she can borrow the $5 and use the extra $0.50 per year to pay the interests on the loan.