The correct answer is option 2. Ampicillin is obtained from a bacterium. Antibiotics are substances that can inhibit the growth of or destroy bacteria. Ampicillin, specifically, is a type of penicillin antibiotic that is derived from a bacterium known as Penicillium chrysogenum. This bacterium produces a compound called penicillin, which can be modified through chemical processes to create ampicillin. Ampicillin is effective against a wide range of bacterial infections and is commonly used in medical settings. It is important to note that while options 1 and 4 mention synthetic drugs, and option 3 mentions a plant extract, these descriptions do not apply to ampicillin.