One of the most common causes of pneumonia is Streptococcus pneumoniae, a gram-positive bacterium. Surrounding the bacterium is a thick structural component layer known as a capsule. This capsule is made up of repeating molecular units and serves as a sticky, protective macromolecule. There are over 84 known different molecular configurations of capsule, and it is the primary component of vaccines against this organism. The capsule is the antigen that we commonly detect in the serology testing referred to in the previous question. Based on the information given about capsules, which of the following types of molecules would you suspect comprises an S. pneumoniae capsule? 1. monosaccharide carbohydrate 2. triglyceride lipid 3. polysaccharide carbohydrate 4. disaccharide carbohydrate 5. adenosine triphosphate