The correct answer is (b). Penicillin is a group of antibiotics that are produced by the fungus Penicillium. It is one of the most widely used antibiotics in the world, and is effective against a wide range of bacteria. Penicillin was discovered in 1928 by Alexander Fleming, and has since saved countless lives.
(a) Bacteria are single-celled organisms that are found in almost every environment on Earth. They can be beneficial or harmful, and some bacteria can cause disease.
(c) Algae are a diverse group of photosynthetic organisms that are found in both aquatic and terrestrial environments. They can be unicellular or multicellular, and some algae can cause harmful algal blooms.
(d) Lichens are a symbiotic relationship between a fungus and an alga or cyanobacterium. They are found in a variety of habitats, including on rocks, trees, and soil. Lichens are not known to produce antibiotics.