Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
Example: In 1582 the united provinces invited francis, duke of anjou to lead them; but after a failed attempt to take antwerp in 1583, the duke left the netherlands again. after the assassination of william of orange (10 july 1584), both henry iii of france and elizabeth i of england declined the offer of sovereignty. however, the latter agreed to turn the united provinces into a protectorate of england (treaty of nonsuch, 1585), and sent the earl of leicester as governor-general. this was unsuccessful and in 1588 the provinces became a confederacy. the union of utrecht is regarded as the foundation of the republic of the seven united provinces, which was not recognized by the spanish empire until the peace of westphalia in 1648.
Example solution: In what year did francis, duke of anjou leave the netherlands?
Example explanation: The generated question is perfect. Because the question is based on second sentence of the input passage and its answer is 1583.

Problem: Denosumab is a human monoclonal antibody which specifically blocks receptor activator of nuclear factor B ligand and is a very potent antiresorptive drug. Its efficacy in reducing the risk of vertebral, hip and nonskeletal fracture has been proven in a large prospective, randomized multicenter study of 7808 postmenopausal women with osteoporosis [Fracture Reduction Evaluation of Denosumab in Osteoporosis Every 6 Months (FREEDOM) trial]. Denosumab causes somewhat greater increases in bone mineral density (BMD) than the class of bisphosphonate antiresorptives. Denosumab also causes an increase in bone mass and bone strength in the spine, ultradistal and diaphysis of the radius, proximal tibia and the hip. Recently long-term treatment with denosumab has been shown to cause a continued almost linear increase in total hip and femoral neck BMD beyond 3 years up to 8 years. In this respect, denosumab seems to differ from the bisphosphonate group in which the rate of improvement of BMD diminishes and for some drugs becomes negative after 3-4 years when the process of secondary mineralization flattens out. This unique property of an antiresorptive drug points towards mechanisms of action which differ from the bisphosphonate group. Both types of antiresorptives decrease cortical porosity but contrary to bisphosphonates the reduction in cortical porosity continues with denosumab which, in addition, also seems to cause a slight continuous modeling-based formation of new bone despite suppression of bone remodeling. The net effect is an increase in cortical thickening and bone mass, and increased strength of cortical bone. This may contribute substantially to the significant further reduction of the nonvertebral fracture risk which was found in the long-term denosumab arm of the FREEDOM extension trial during years 4-7.

Solution: Which is the target of the drug Denosumab?