Partial regulators are the organisms who
(a) Can regulate their body temperature to a large extent of the environmental condition
(b) Change their body temperature to a certain level of ambient temperature but if the temperature
      goes on increasing they can maintain steady temperature.
(c) Can regulate body temperature voluntarily
(d) None of the above

Hint: Warm-blooded humans are regulators as they are able to maintain their temperature and cold- blooded fish are conformers by changing their body temperature according to the environment. Those are termed as complete regulators.

Complete answer:
Animals like shrew, ground squirrel tend to be regulators first and then they can’t maintain homeostasis anymore they become conform. The thermoregulation in animals where they are neither regulators or conformers is turned as partial regulators.
- Organisms are divided into two main groups based on thermoregulation-
Poikilotherms or cold- blooded - Those organisms who can change their body temperature according to the environment like fishes, amphibians and reptiles.
Homeotherms or warm- blooded- Those organisms who can maintain their body temperatures like birds and mammals.
- Modern classification of animals based on heat transfer
Ectotherms- Those organisms which take heat from the outside like fish, amphibians, reptiles and invertebrates.
Endotherms - Those organisms which take heat from inside like mammals, birds and some fishes.
Heterotherms - Those organisms which take heat from inside but body temperature change like a bat, hummingbirds.
So, the correct answer is, ‘change their body temperature to a certain level of ambient temperature but if the temperature goes on increasing they can maintain a steady temperature.’

Note: - In reptiles, they conserve heat into the centre of the body. Increase of heat production in response to hormone thyroxine and epinephrine.
- In birds, they regulate temperature by a metabolic process. They don’t have sweat glands, thus loss of heat takes place from gular pouches present in the throat and their fluttering increases evaporation from the respiratory system.