Question: A 72-year-old man with a pathological fracture in the left femur goes to the Emergency Department. After the surgical intervention, the diagnostic study was performed to find out the underlying pathology with the following findings: hemoglobin 9.5 g / dl, total protein 11 g / dl, (VN: 6-8 g / dl), serum albumin 2 g / dl, (VN 3.5-5.0 g / dl), beta 2 microglobulin 6 mg / l (VN 1.1-2.4 mg / l), serum creatinine 1.8 mg / dl (VN: 0 , 1-1.4 mg / dl). Indicate what would be the diagnostic tests necessary to confirm the most probable diagnosis: 
 Options:  <1> Radiological bone series and bone marrow aspiration. <2> Serum and urinary electrophoresis and renal function tests. <3> Bone marrow aspirate and serum calcium concentration. <4> Bone marrow aspiration and serum and urinary electrophoresis. <5> Biopsy of the pathological fracture and radiological bone series.
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