The correct option is B Testudines
Birds (Aves) and mammals (Mammalia) are homeotherms, which means that they can maintain a constant body temperature.
Macropus and Camelus are mammals and hence, are homeotherms. Columbidae refers to a family of birds that consist of pigeons and doves. They are homoeotherms.
Testudines belong to Reptilia. They are poikilotherms, which means that they cannot maintain constant body temperature with resepect to changing external environment temperature.