Answer:
Option a, survive in extreme environments
Step-by-step explanation:
Both Thermus and Deinococcus belong to the group of bacteria that are collectively termed as Deinococcus–Thermus group.
Deinococcus are radiation-resistant vegetative cell as they are able to resist ionising radiation. Also some species of Deinococcus are thermophile.
Thermus are thermophilic bacteria that are able to live in extreme temperature condition and thus are able to tolerate high temperature.
Hence, option A is correct.