An unknown compound weighing 0.0020 g with a molecular weight approximately equal to glucose (180 g/mol) was dissolved in water with a total volume of about 5.0 × 10² mL. A portion of this solution was placed in a 1.0 cm cell, and the UV spectrum was measured. The solution had λ_max = 260 nm, with A = 1.0. Calculate the molar absorptivity at 260 nm.