(a) liquidate such investments in the market, in which case each affected sinking fund account shall be credited with its pro rata share of the sales price thereof less expenses incurred in connection with the sale (including without limitation applicable brokerage fees or charges); or

(b) purchase such investments with amounts on deposit in other sinking fund accounts at the fair market value thereof, in which case each transferor sinking fund account shall be credited with its pro rata share of the fair market value thereof (as certified by a dealer in such investments).