help for bio?

2.) A 63 year old male complains of a 6 month old history of difficulty voiding and feeling as though he cannot empty his bladder completely. After voiding, he often feels as though he needs to urinate again. He denies urethral discharge or burning with urination. He has had mild hypertension and takes thiazide diuretic. His only other medication has been ampicillin for two urinary tract infections during the previous year. On examination, his bllod pressure is 130/84 mm Hg, Pulse rate is 80 beats/min, and he is without fever (afebrile). The heart and lung examinations are normal and the abdominal examination shows no masses.

What is the most likely diagnosis?

What is the anatomical explanation for the patient's symptoms?

please add links if dont know.