The parents of a male infant report that male children over three generations in the mother's family have been affected by a progressive disorder involving multiple organ systems. These children have had coarse facial features, corneal clouding, joint stiffness, hepatosplenomegaly, and mental retardation, and many died in childhood. At autopsy, some of the children had subendothelial coronary arterial deposits that caused myocardial infarction. Laboratory testing of the infant now shows increased urinary excretion of mucopolysaccharides. Bone marrow biopsy is performed, and the accumulated mucopolysaccharides are found in macrophages ("balloon cells" filled with minute vacuoles). Which of the following enzyme deficiencies is most likely to be seen in this infant?