A 40 year old male patient presented with mild abdominal pain, mild constipation with a feeling of incomplete evacuation and mucus in stools for the past 4 years.On examination, tenderness is present in left iliac fossa.The most likely diagnosis is -

• A. Ulcerative colitis
• B. Diverticular disease of the colon
• C. Irritable bowel syndrome
• D. Ca colon