The correct option is B Bacillus and Clostridium
An endospore is a dormant, tough, and non-reproductive structure produced by certain bacteria. Endospore formation is usually triggered by a lack of nutrients and usually occurs in gram-positive bacteria. Endospores enable bacteria to lie dormant for extended periods, even centuries. When the environment becomes more favorable, the endospore can reactivate itself to the vegetative state. Examples of bacteria that can form endospores include Bacillus and Clostridium. Thus the correct answer is option B.