The correct option is B Endospores.
A bacterium capable of tolerating extreme heat, dryness and toxic chemicals is probably having endospores. Endospores are highly thick-walled and resistant spores which are formed in response to adverse environment, presence of harmful waste products or ageing of bacterial colony. Endospores can easily tolerate a temperature of ±100 degree celcius. Toxic chemicals have no effect on them. The resistant nature of endospores is due to their thick wall, low water content and the presence of an anticoagulant chemical known as dipicolinic acid. Fortunately, only two pathogenic bacteria Clostridium tetani and Bacillus anthracis produce endospores.