<prompt> Please answer with one of the option in the bracket. Write reasoning in between . Write answer in between .Q:A 72-year-old man goes to his primary care provider for a checkup after some blood work showed lymphocytosis 3 months ago. He says he has been feeling a bit more tired lately but doesnt complain of any other symptoms. Past medical history is significant for hypertension and hyperlipidemia. He takes lisinopril, hydrochlorothiazide, and atorvastatin. Additionally, his right hip was replaced three years ago due to osteoarthritis. Family history is noncontributory. He drinks socially and does not smoke. Today, he has a heart rate of 95min, respiratory rate of 17min, blood pressure of 13585 mm Hg, and temperature of 36.8C 98.2F. On physical exam, he looks well. His heartbeat has a regular rate and rhythm and lungs that are clear to auscultation bilaterally. Additionally, he has mild lymphadenopathy of his cervical lymph nodes. A complete blood count with differential shows the following:Leukocyte count 5,000mm3Red blood cell count 3.1 millionmm3Hemoglobin 11.0 gdLMCV 95 um3MCH 29 pgcellPlatelet count 150,000mm3Neutrophils 40Lymphocytes 40Monocytes 5A specimen is sent for flow cytometry that shows a population that is CD 5, 19, 20, 23 positive. Which of the following is the most likely diagnosis?? A: Aplastic anemia, B: Chronic lymphocytic leukemia, C: Tuberculosis, D: Acute lymphoblastic leukemia, E: Immune thrombocytopenic purpura,  <response>: Based on the information provided in the question stem, the key findings are:- 72-year-old man with lymphocytosis on blood work 3 months ago- Feeling more tired lately, otherwise asymptomatic - Mild cervical lymphadenopathy on exam- CBC shows lymphocytosis 40, normal RBCs, low platelets- Flow cytometry shows CD5, 19, 20, 23 positive populationThis presentation is most consistent with a chronic lymphoproliferative disorder like chronic lymphocytic leukemia CLL, given the lymphocytosis, lymphadenopathy, and flow cytometry findings. The flow cytometry showing a CD5, 19, 20, 23 positive population points towards B-cell CLL specifically.Aplastic anemia would show pancytopenia. Tuberculosis would not have these flow cytometry findings. Acute lymphoblastic leukemia and ITP do not fit with the chronic presentation here.Therefore, the most likely diagnosis is chronic lymphocytic leukemia.B: Chronic lymphocytic leukemia 