Recently physicians have determined that stomach ulcers are not caused by stress, alcohol, or rich foods, but a bacterium that dwells in the mucous lining of the stomach.

• Anot caused by stress, alcohol, or rich foods, but  
• Bnot caused by stress, alcohol, or rich foods, but are by  
• Ccaused not by stress, alcohol, or rich foods, but by  
• Dcaused not by stress, alcohol, and rich foods, but  
• Ecaused not by stress, alcohol, and rich foods, but are by