Step 1: Understanding the Concept
Organisms respond to environmental changes either by regulating or by conforming.
Step 2: Conformers
Conformers cannot maintain a constant internal environment. Their body temperature and osmotic concentration change with the surroundings.
Step 3: Other terms
Regulators keep these constant, migrants move away from stress, and organisms that suspend activity show hibernation, aestivation or diapause.
Final Answer:
Conformers are organisms whose body temperature and osmotic concentration change with the surroundings.
\[ \boxed{\text{(B) }\text{whose body temperature and osmotic concentration changes with that of surrounding}} \]