The nucleophile attacks either of the carbonyls. the resulting hydride attacks the carbonyl adjacent to the one which just got attacked (*), forming the alcohol. Since the remaining carbonyls are meta to the CH2OH and COO- groups, we will consider inductive effect of the carboxylate in preference to that of the CH2OH group(*). Consequently the carbonyl attached to the "carboxylate" ring undergoes attack by the incoming nucleophile.
Please consider the star-marked points, and analyse their validity...
My assumptions:
Excess of base,
Kinetically controlled reaction.