What term is used for bacteria that can survive in harsh conditions?

The term that describes bacteria capable of surviving in harsh conditions is "extremophiles." Extremophiles are a specialized group of microorganisms that thrive in environments that are extreme in terms of temperature, pH, salinity, and pressure. These conditions are often inhospitable to most other forms of life, which is why extremists are so intriguing to scientists. For instance, some extremophiles can survive in boiling hot springs, deep-sea hydrothermal vents, or extremely acidic environments.

Other terms provided in the options refer to different characteristics of bacteria. Pathogens specifically denote organisms that cause disease, while halophiles are a type of extremophile that specifically thrives in high-salt environments. Obligate aerobes are bacteria that require oxygen for growth, which does not necessarily relate to their ability to survive harsh conditions. Hence, extremophiles is the most accurate term for those bacteria that can endure extreme environmental challenges.